The issue has been fixed in InDesign 16.4.
Please update your copy of InDesign to this latest version to get the fix.
Adobe InDesign team
An error occurred while saving the commentJumpstation commented
We have experienced this same missing equation issue when we place a Word file with Mathtype equations into InDesign 16.3.
We have rolled back to InDesign 15.1.3 where the equations display correctly.
Is there is a fix for this issue in InDesign 16.3 yet?