Hi Teresa,
First thing I would try is resetting the registries. This will return 202o to its original settings and will usually resolve odd issues like that.
To reset the registries go into the maintenance tools for 2020 – for version 11 the Icon is an orange circle with a wrench and a screwdriver in it – and select 2020 Design Registry Reset. Once you have done that, close the maintenance tools and reopen 2020 design and see if it worked.
Neil