Hello there!
We've found a bug when it comes to filtering and collapsing groups, if a group is collapsed and we filter for something that will not return it, the group is completely removed.
To replicate using the demo https://www.bryntum.com/examples/grid/filterbar/
Remove the existing Paris Filter
Group by city
Collapse some of the groups
Filter by a city
When removing the filter, the non-matching cities, with collapsed groups will disappear from the grid
You can remove every single item from the grid this way if you wished.
Repeat steps above
Collapse all the remaining groups
Filter by one of the removed cities
Remove the filter
All groups will now be gone
If you have any idea how to do a workaround for this in the meantime, that would be great.
I have attached a video zip file with a video showing how to replicate it using the Filter example.
Thanks.