This is a option in PERSONALIZE menu : DIS(able) PAGE AUTOCOPY.
I tested wit> Blockquoteh and without this option.
@sezare56 Legend! This fixed it so thank you! It’s so strange I hadn’t had this issue before as I’m a long time OT user. I’ve got a feeling I always just used different length ‘scales’ straight away.
It’s great this is documented now for future reference as this has saved a lot of pain with just a simple parameter setting.
Case closed. 
I just tested with autocopy page on and with autocopy page disabled. I set pattern scale to 32/32, then activated per track.
It does not lose trigs on the second page.
I usually go to pattern settings right from the scale menu, but even if I close the scale menu, then later open pattern settings and activate per track, no difference (it shouldn’t make a difference, but I just tried different things to check) - it keeps trigs.
Btw, I’m on an Mk1 with 1.40A btw.
Ok, the plot does thicken. You are correct! My recent experience wasn’t that so I thought I’d test that again with a new pattern and now it’s working correctly with the AUTOCOPY either on or off!??!
I don’t have my original version I had the issue with so it may have been some pattern/track setting in there that could have been triggering this issue?? WEIRD. Also explains why I’d never come across this problem after years of using the OT. The AUTOCOPY off did fix the issue though on the original pattern so handy to know regardless.
Ok, so case kinda closed?! 
Sometimes weird things happen, it’s usually gone after reloading the project. Happens to me once or twice a year.
Yeah and also glad it keeps the trigs. It would’ve been pretty unfortunate if one could lose trigs that way.