Welcome Paul,
Please share your code if possible. In LVGL v9.1, the way draw event callbacks are handled has changed slightly, this may be part of the issue. Previously someone here had a similar question, see my answer there: Custom cell-draw in lv_table V9 - #2 by Tinus
Hope this helps somewhat but without seeing your code I cannot draw any conclusions on what’s wrong, seems like you are missing a typecast somewhere.