Glitch when playing in Sync group

Hi

I am on Xibo 4.0.6 CMS and I have created a sync group of 3 displays. There is a slight glitch in the playback of the layouts which causing the feature of sync group to be useless in such case. What would the problem be?

I am using TX3 android players (4GB + 32 GB) and using Xibo 4.0.3. A video that shows the problem is in the link below.

Thanks in advance for any help.

Regards
Micke