Welcome, @Heather_Peterson,
When you search for one of these tasks, click open the right-side task detail pane.
Confirm that you are the Assignee. (If not, that’s the problem.)
If you are the Assignee, then look to the right of that field and see what section the task is in. Make sure that section is visible and open in your My Tasks to see the task there. If you still can’t see it, check your My Tasks Filters, Sort and Group by in the right-side header and try relaxing those.
If all that fails, contact Support, which temporarily is:
Thanks,
Larry