Problems when trying to record or view 2+ programmes at once - AGC to blame and/or something else?

[cerebros]

Hi everyone

I'm not quite sure if I've got one or two problems at the moment.

After my Humax Freesat box died, taking quite a lot of recordings with it, I found out about Plex DVR and using Enigma2 boxes as tuners for it, and ended up buying a Gigablue UHD UE 4K and installed a new LNB to feed it on my dish.

The initial problem I saw was that I was setting recordings in Plex DVR that then didn't record. I thought I'd finally got to the bottom of that when I found out that new airings aren't always marked as such in the EPG Plex uses. I went through and updated all the recordings I'd set and thought everything was now working as expected when I saw that current series of The Handmaid's Tale I'm recording from Channel 4 had recorded this week.

Unfortunately, any chance of being in the wife's good books for this working vanished when we sat down to watch it and found the recording was unwatchable due to constant freezes, sound cutting out and the picture degenerating into a mess of squares. (Have tried to do some screen caps which should be in the attachments)

This was the first time I'd had this happen - up til now recordings had all been fine.

When the wife went to bed I thought I'd better check out the episode of SAS Rogue Heroes I'd recorded that aired at the same time as The Handmaid's Tale. That recording exhibited the same issues. However, the recording of the Formula 1 highlights on Channel 4 that started about an hour after those two recordings didn't have any issues.

I've done some test recordings and viewings and as far as I can tell, the issue occurs when more than one tuner is in use. If I watch live TV through Plex on my desktop, everything is fine up until I start watching another channel on my phone or via my Fire TV stick.

I've updated my Plex instance to the latest version (1.30.0.6359-7000) which made no difference. I updated the firmware on my Gigablue a few weeks ago when I was trying to sort out the issue of recordings not happening, although I think there may be a newer firmware since (I'm somewhat reluctant to do firmware updates since it meant having to set the box up from scratch again)

However, having finally found my through the menus to a signal strength screen I'm guessing that the "AGC" might be an issue? As per the attached image, I had an SNR of 94% but an AGC of just 8%, which I'm assuming isn't terribly good.

So, my questions are, is a low AGC likely to be the cause of the issues I'm seeing when trying to use more than one tuner at a time, and how do I improve the AGC?