So, in true 'spoke too soon' fashion... the last 3 days with the 10.1 update of FCPX has been a nightmare. At first, everything worked...really fast....then i had to do a few complete re-renders of the whole 97min timeline. That's when the fun started. First of all... it crashed... it just disappeared and completely closed down. But, i did have the 'snapshot' back-ups. It didn't matter... they crashed as soon as i tried to render too.
I used Digital Rebellion's excellent crash analyser to help me diagnose the problem, but each time it crashed, it gave a different answer... sometimes it was a motion effect, other times a graphic's card issue...and sometimes it was a GUI problem. When i disabled all my plug-ins... FCPX worked fine, but without them, i can't continue my project. So, one by one i began to put them back.... here's what i learnt:
Magic Bullet Looks (latest update) = Works fine.
Magic Bullet Mojo = Works fine.
MotionVFX mLooks = Works fine.
MotionVFX mFlare = Slow to load, but works fine.
Neat Noise Reduction = Latest version 3.5 works but you need to delete and replace earlier versions in your timeline - even though they will just update... you need to manually replace them or there are render problems.
CrumblePop Plugs = Works fine.
MyFCPeffects = Works fine.
TKY Effects = All fine.
A4D = All fine.
Pixel Film Studios = Hmmmm.... problems. ProLens causes issues... specifically the Graduated Filter. Nearly always crashes and sometimes flickers... then crashes. ProLumetric = suspect. ProSlice = suspect.
Any Custom Titles created in earlier versions of Motion = Very suspect... it doesn't like them.
10.1 is good... i love the new Library features and i really like the speed, the re-timing updates and lots of the other little updates, BUT... it's jumpy. It needs a 10.1.1 update soon and all the plug-in companies need to do more extensive testing. It's no good if you can't stack effects.
Anyway, if you're going to risk it, Use SupaDuper to make a clone of your System Drive before you do anything... and then completely remove 10.0.9 including the preference files and cache files. Then use the now free Event Manager X to import your projects one at a time... don't just open FCPX!!! This is really important. Open Event Manager X, select everything you want in a library and then open FCPX.... then close it down and do it again for each project. Once you've combined projects and events into a library, that's it... so get it right first time.
I'm aware that my problems with 10.1 are mostly 3rd party plug-in related and that most people just running the app on it's own will have few if any problems, but 3rd party effects are vital to me and without them, i can't use 10.1.
I'm going back to 10.0.9 for now until i can find a solution to get 10.1 stable... but i think it will need an update as well as some of the plug-ins.
I guess this just goes to show that doing a major update during a big project is a bad idea. But, i was covered by proper back-ups and clones of my system. Make sure you do the same.
For those wondering if this was caused by a corrupt clip or project file... it's possible, but i ran the corrupt clip finder and copied and pasted the entire timeline into a new project, so i don't think so.
Anyway, it's all working fine again in 10.0.9, so i'll wait to try the update again when it's been out in the open for a bit longer.
EDIT - Typical... the very next day Apple releases the 10.1.1 update that appears to fix most of the issues i was having. I'm going to give it another go and see what happens... i'll post on my results soon.
Apple FCPX 10.1.1 Release notes: