It is, I don’t know what the status is on Tsurakame.
EDIT: [iOS] Tsurukame - native app with offline lessons and reviews - #1125 by marciska
Apparently a fix is in the work but not upstreamed yet?
The post also lists a workaround to temporarily remove kana vocab from the app. Apparently the issue is with する that’s handled specially by the app because it considers it a suru-verb (ironic).