The fix for this issue is now available in the latest update of InDesign – that is, InDesign 15.0.3.
Please update your InDesign application to get the fix.
Adobe InDesign team
An error occurred while saving the commentAnonymous commented
Spell check not working here either. 15.1.1 Neither Hunspell or Proximity work. Before the update one of the two worked but now nothing.