Unable to do a search using tag
Can you check if the tag you selected is a parent tag and has child tags? If yes than this is a known bug on 5.35.1 when doing a search on parent tag and is logged at https://lab.civicrm.org/dev/core/-/issues/2502 and is fixed as part of 5.38 release.
Solution(one of the below):

Use 'IN' operator instead of '='.
Apply patch from here.
Wait for 5.38.0 release