THIS EXACT ISSUE HAPPENED TO ME 
The intervals on my anki and ankidroid were not matching and I was being driven insane. I spent a couple hours trying to figure out why. I then copied the FSRS parameters from desktop to android, and it still didnt get fixed. but then when I went android to desktop it said āneed 17 parametersā and then I was like, huh that is weird. Then I found this 17 vs 19 parameters thing. Updated Anki on desktop and that fixed it but it was a tense few hours.
I can understand how frustrated you might be feeling while trying to debug this. But, glad to hear that you finally figured it out.
@David, letās do one thing to prevent other users from having a similar experience with the future updates.
AnkiDroid shows changelog just after updating. IMO, that would be the best place to prominently say that the user might want to update to the corresponding desktop version for best experience, especially when we have scheduler changes like this.
Because AnkiDroid is updated automatically and Anki isnāt, many users will get the latest update on AnkiDroid before they will get the same on desktop.
Thanks for the reply. One suggestion, if I may, might be that this be added to the app store description as a note at the bottom? Since when I had this issue, I went there to check if there is anything new in the update but couldnāt find anything.
Completely agreed. Thanks!
Play Store Description updated