Precondition: Have an active problem whose name contains multiple consecutive spaces. Example: 

Second test   trigger   with tag priority 

Steps to reproduce:

1. Go to Monitoring → Problems.
2. In the Problem filter field, enter the problem name including the multiple consecutive spaces (as in the example above).

Result:
The problem list is empty.

Expected:
The filter should correctly find problems even if their names contain multiple consecutive spaces.
Note: The same filtering approach works correctly on the Hosts and Latest data pages.