Unable to Highlight to Create Segment

Hello. When annotating a video, the software will be working fine and then randomly stop allowing me to highlight (click and drag) to create a new segment. I am also unable to use “Selection Mode” to highlight and create segments. We have tried opening and closing the program and restarting the computer, but nothing brings back the ability to highlight. While this doesn’t happen often, it happens enough that it is becoming quite a hassle. How can I fix this problem?

Additional info: We are using ELAN 6.4 with MP4 videos. Software is on a Windows desktop.

Hello,

Regarding the “selection mode” and selecting by clicking and dragging, are you facing this issue on top level tier ? Does it occur on multiple tiers or just with one tier ?
What is the media framework used ? You can know that from Edit → Preferences → Edit Preferences ->Platfform/OS

Could you check if you encounter the same problems with e.g. one of the ACLEW example sets that can be downloaded from this resources page

Best Regards
Divya