Having the same issues with 3 different zgemma boxes, at 3 different addresses, 2 different ISP's and 4 different subs/providers.
All ran fine till pretty recently.
2 of the boxes are hard wired, 1 homeplugs.
All the subs run fine on VLC Media Player on a laptop and on Perfect Player on the firestick.
I reflashed my box with an old version of ipab that I used when the iptv worked fine to rule out it being an ipab update.
Have reflashed boxes and reinstalled scripts.