Those are typically pertaining to a book on either your wish list or else completed read list.  Someone is liking that you have that particular book on your list to read or likes the rating you gave it.  I'm not clear whether those individuals are promoting that book for a friend or possibly just really are liking that others are interested in the particular book.  It's a Goodreads thing, with Goodreads primarily focused on readers.  Thus, readers can comment and like whatever they want.  I merely ignore them as they don't really pertain to me or my books.

I did exactly that for several months last year, prior to publishing #6 in my series.  For a couple of months, I did see some increased sales on my other four books but then, not so much, in spite of advertising on all the usual sites.  It was easier getting slots on those sites since I was not restricted to any specific dates.  Although iBooks and D2D reports showed hundreds of downloads of my permafree book #1, I don't think I really got enough traction.  And, I had no luck getting a BookBub.  All this was before I used any AMS ads.  Perhaps the biggest benefit for me was seeing how the ad sites compared since I was booking them on separate dates.

I unpublished wide, put book #1 back in KU, priced it at $2.99 and am convinced I've made more money since.  I also put my first three books in a box set, also in KU (it was necessary for book #1 to be back in KU in order for me to do that).  Still, no BookBub (I had hoped maybe the boxset at $0.99 might get me one).  Sadly, I suspect being exclusive makes getting any BookBub deal much more difficult.  I published book #6 a year ago and that gave me a huge boost in sales on all books for a couple months.  I've been using AMS ads since to sustain sales.  Over half my income is from KU.  Hopefully, I'll finish book #7 soon and get another boost in sales.  We'll see!  Others obviously have done well going wide but for me, with the fantasy series which I'm writing, I believe staying in KU is best.

I think Amazon handled this exactly right. And I seldom agree with them :-)

I'm merely a prawn but two of my six KU books were affected by this; here's what I am receiving for the audiobooks which they say were given away during this situation:

Missy the Werecat (Unabridged)                   P. G. Allison   US   20.00%   21   $24.95   $104.79
Missy's Misadventure:
Missy the Werecat, Book 4 (Unabridged)   P. G. Allison   US   40.00%   17   $24.95   $169.66
                                                                      Grand Total   38                   $274.45

I don't plan on complaining.

I was not aware my audiobooks had been affected but I just received this email from ACX:

Dear P. G. Allison,
We are contacting you today regarding an update to your ACX earnings. We recently found that due to a technical issue, your audiobook(s) were included in the Kindle Unlimited program in error. We have removed your audiobook(s) from Kindle Unlimited and apologize for the mistake.

For each Kindle Unlimited subscriber who downloaded your audiobook, you will earn the same royalty as you would earn for an a la carte (ALC) sale at list price on Audible. Your earnings from the inclusion in Kindle Unlimited and related download data will be provided to you alongside your July Earnings Reports, which you will receive no later than August 31.

We sincerely apologize for any inconvenience this has caused.

Kindly,
The ACX Team

Have others received this message as well?  Does the stated royalty payment seem appropriate and adequate?

I have zero reads showing today.  After a month showing 5K or better reads, the last few days have dropped to 3K and then 2K, consistent with what the OP has stated.

Mine has not updated since April 3rd.  Glad it's not only me.

Thanks to finally releasing another book, all six in my Missy the Werecat Series are currently in the top 100 for the Superhero category:

          Kindle Store > Kindle eBooks > Science Fiction & Fantasy > Fantasy > Superhero

Having a Newsletter definitely helped.  Book I is permafree and at #5 in the free category while the other five are in the paid category. 

Update!  Late yesterday Amazon did list my book as FREE again and today I received a message from KDP Support saying "they have fixed the error".  Although apologizing for the inconvenience, no explanation was provided for why this glitch occurred.  I'm relieved this was fixed within a day and things are back to normal, with my book's rank now hovering around 1000 in the Free Kindle Store.  Evidently, my promo ads are working and I haven't ended up losing much.  Wheh!

On Feb 16th, after pulling Book I in my series from KU, going wide and publishing it for FREE in B&N, Apple & Kobo, I sent Amazon a request via KDP Support (Amazon Product Page, Price Matching) to please price match, providing them the corresponding links to these other sites.  On Feb 17th, they did so in most stores but delayed doing so in US until Feb 19.  They sent me an email on Feb 23rd saying it was now FREE in all Kindle stores.  Soooo, I thought I was now permafree and have paid for a couple ads.

Today, I see it is back to $3.99 in the US.  It seems to still be free in their other stores.  Is this merely a temporary glitch?  I've sent KDP Support an email but I'm not sure how long it will take to receive a response.  Have others had this happen?  Should I do something else?

I like what was posted on this issue a year ago:

https://www.kboards.com/index.php/topic,216022.msg3011147.html#msg3011147

So far, all my writing has been without any outline; the books have simply evolved as I kept working to make various things happen for my characters, often with surprises as I went along.  While I typically will have a vague goal and direction, I have not yet managed to write down an outline of any kind.  All attempts to do so have met with my staring at a blank page for far too long and giving up.

Submission complete!

Best of luck, Pippa!  I've just downloaded your boxed set; hopefully, that will help!  I'd read the first book earlier and enjoyed it.  I really like the way you've hit all your milestones so far!