inspector blank on some projects

5674738--591628--upload_2020-4-5_18-10-24.png
^
what's that weird looking icon?

bug# 1234152

it happens on a 4.7 project converted to 5.6 then 2017 then 2020
same 4.7 project opened in 2020 without the in between steps is fine but not when opened initially, it had the same symptoms
I think i deleted the project settings or the user settings and things were fine afterwards