I see the expected timecode window graphic glitch.
Had to reinstall LUTx.
Did oper Color Finale from main applications folder before running it as suggested in Denver's mail. And it now seems to work fine.
One other weird thing: I run FCPX on a 2012 Retina MacBook Pro with a second monitor. I have the viewer on the MacBook Pro Retina display and everything else on the second monitor. But everytime I open FCPX now they've flipped so viewer is on second display. Slightly annoying, but can't decide if it's annoying enough to go back.
Logic Pro X re-scanned all the Audio Units (FCPX didn't) but seems to run fine.
I used the Ultra MiniMonitor today and it seemed to be working. It did quit FCPX on me once (I could tell by the plugin alert on quit) To be honest I've found the MiniMonitor caused issues before Sierra - causing FCPX to quit or freeze. Tried reinstalling and didn't make much difference.
FCPX is crashing on me relatively frequently (about once per hour) with different process problems each time - although the crashing is not enough to be annoying (& no where nearly as often as the first few months with El Cap!), hopefully they'll sort it out soon.
As Peter says, use caution!
Back-up, Clone, run on separate drive/partition if you can.
YM-Will-V. Just the nature of bugs. People have issues because they may have some software/hardware that has a problem, others with same computer w/o that one piece of problematic addition have no issues.
There are various reports about USB issues, so check compatibility for all USB devices.
Logitec is reporting issues with LCC and mice going crazy.
Audio interfaces are showing problems, check manufactures website for compatibility/new drivers/firmware.
There is the monitor issue with 4K and setting resolutions. Dell seems to be affected.
Both Seagate and WD have new drivers/firmware so make sure you are up to date.
Several threads on Apple Support Pages that often are being linked to USB drivers.
Some kext files are breaking.
Siri sometimes needs to have the audio source selected a couple of times to work. Also be aware if using some BT audio devices, Siri lowers the sampling rate so if you have crappy device, you may have issues. She also doesn't like noisy environments so much.
Reports that CS5/6 are breaking and Adobe most likely doesn't care but you are free to sign up for CC.
As noted here on this thread some plug-ins need updating.
Make sure FX Factory is up to date.
There are numerous under the hood OS changes for analyzing and indexing files/data so when you update expect your computer to go into overdrive, be sluggish and maybe run hot for a long time. Plug it in and let run overnight at least.
Photos especially is doing lots of "magic" behind the scenes so if you have very large libraries, expect very long and CPU intensive analyzing to happen. Some reports saying days.
Roaring Apps is showing lots of ?? about compatibility issues, not a bad place to start looking. roaringapps.com
Search is your best friend.
Expect Apple to release several updates to fix bugs so update often.
Hope not too off topic as not just FCPX
I'm from Sweden, now living in Germany. I have always ordered my Macs with English keyboard and installed ENglish system... Not only do the translations tend to be strange (most of cimputer lingo is english by origin anyway) but also most applications are in English, only the major ones tend to be translated... so key commands / shortcuts tend to be weird or not work at all if you have a non-english keyboard... If one understan english I see no reason to use your Mac in any other language... It's just begging for trouble...
It's just a quick learning curve. I write the Swedish å ä ö all the time with no trouble, and Straße is really easy to write (just alt-s to get ß). Ü is also easy once you get used to it (alt-u then u again).
Well worth it not to have to use macOS in Swedish or German or have to use Swedish or German keyboards (especially the German ones, they're bonkers!)
But sorry, we're getting side-tracked.
After some more work in FCPX with Sierra it seems like it's just the issue of it not remembering which monitor the windows were on and the little timecode graphical glitch. Haven't come across any more issues than that so far!
I'm having some issues in Logic Pro were some project can't load some samples, but not sure if that is because Sierra or the new version of the sample playback plug-in, PLAY 5), other than that everything seems hunky dory there as well)