Channels clearing fine, recordings sometimes have glitches

[Sawboss]

Setup:

Virgin Media
Zgemma H4
multiple n: lines via oscam
Latest Grogbuild

The channels are clearing fine. There's no noticeable glitching while watching live TV, but they're very rare so maybe I've just not seen them. There are no missed ECMs.

When recording (either to USB drive - tried several - or to a network share) there are occasional glitches, video and/or audio. It's not every recording and it happens maybe once or twice in the recordings it *does* happen to.

Signal strength is very strong. Maybe too strong? Would an attenuator help? Any ideas or suggestions would be very appreciated.

 

[Sawboss]

Well I got an attenuator, and it doesn't help. Still random glitches in recordings.

I've tried each of the tuners on its own too, and it's apparent across all three tuners.