When there is a selected item and filtering is performed in the Gantt, sometimes a task in the new filter result is displayed as selected.
Sometimes the task with ID 11 is marked as selected. The issue does not appear consistently, so you may need to perform the test multiple times.
screencast - https://somup.com/c0XZ6DgaRA
The tasks that have not been selected, should not be displayed as selected after filtering.