I do not know if we can qualify this problem as a bug, but it is very annoying in the use of SC. (already existed in 20.02)
Double click on. a clip in the playlist.
In the player, define the IN and OUT points.
Type A to add the clip to the active timeline track, the clip is added and it is selected (outlined in red)
In the “Filter” tab, select a filter which has input fields (for example: Crop rectangle)
Enter a value in the zone “Position” and confirm with the ENTER key
The focus returns to the player, the clip in the timeline is no longer selected. You must therefore select the clip again, then the filter before you can enter the second value.
Some time I do have a similar problem but when I click on (for exemple size and position), to change the setting the filter does not respond, even if I do click on visiluation windows ?
W10
The problem is that Enter is also delivered to the global shortcut handler which says to open the current playlist item (see Keyboard Shortcuts reference). The workaround is to use Tab to apply the change. I realize this is unfriendly. Moreover, it is not limited to Filters, it also affects Properties (every variant), Export, and Recent. I could work on a change to every UI panel and try to remember to do that for every new one. However, there are and will continue to be more pitfalls. So, I am changing this shortcut to Ctrl+Enter (Cmd+Return for macOS) for the next version 20.06.