This started maybe a week ago, perhaps with the recent update? When doing my lessons on my android and progressing to the quiz, the displayed vocab/kanji does not change. The same vocab will be displayed and i keep getting it wrong, but when i review the correct answer it isnt matching the vocab displayed. Seems to be working fine on my computer though, and reviews on my phone is also working fine. I hope that makes sense, and thanks for the help.
Which app are you using? Or is this on the mobile website?
Same here 
Im using the WK app, if thats what you mean. I didnt know there was more than one, is there something specific i should look for?
I was using WK for Android and experiencing same issues. Seems that the kanji/vocab displayed is different than the real requested.
I suggest using other apps since WK app uses the API v.1 which is going to sunset in September.
Flaming Durtles uses the V2 API and is available here: https://play.google.com/store/apps/details?id=com.the_tinkering.wk&hl=fr_CH
It even has offline support and other userscript inspired features!
There is no official app for WK, and I think one of the apps is using the soon-to-be unusable API v1. I think I read somewhere it’s soon to be unsupported.
As @MafuTofu mentioned, Flaming Durtles might be a good alternative.
Thanks everyone, that fixed it and makes sense. Didn’t realize there was no official app, interesting.