I had this same issue yesterday after I downloaded the lastest update and posted a support ticket. In order to fix it I deleted the app and reinstalled it and it's back to working fine, but I think the fix posted yesterday caused this problem so I did not redownload it again.
To quickly fix the bug in 3.1.0 with people not being able to add tasks, we had to break part of saved search. We thought it was more important to quickly fix adding tasks than to be slower and fix both adding tasks and also keep saved search working 100%. In the next update we will have saved searching working 100% again.
Only certain saved search rules are not working.
1) Date is before X
2) Tag contains X
3) Title contains X
4) Note contains X
All other searches should work correctly. If not, please file a bug report with an example of the search that isn't working.