Filter is unstable

**Describe the bug**
When searching task by image filename, the result returned too quick and is blank from time to time. After changing filter it suddenly work again.

**To Reproduce**
1. open project
2. find task by filename as shown below, the task could not be found. I was pretty sure the task was there, I just exported the dataset.

3. change search condition, the task was found

4. now go back to the first way, now the task could be found too.

**Environment (please complete the following information):**
- Latest label studio community edition, using docker