We had delayed status shown in our sandbox refresh as well. Usually it takes 2 days, it took 6-7 days this time.
After the refresh, we can't do filters on text fields for custom records.
Even though if field x contains lets say text abc.
If we do a filter for field x with field contains / is / startswith abc.
It always comes back empty.
Going to the record editing and updating the field resolves the issue.