I get this "Selected file type is not allowed!" error no matter what I try, or what sort of project I try to export. I can't seem to find a place to actually select a file type, either.
 
Is anyone else getting this error? This seems like a great feature, but for me it's totally non-functional. Or am I missing something?
 
Figured it out: Manually downloaded the latest update for BandLab Assistant, and installed that. Now the export seems to work. 
 
 

I'm also trying to update BandLab Assistant, and getting nothing but "Update Failed. Something went wrong. Please try again." 
 
I wonder if there is some sort of system issue?...

from http://forum.cakewalk.com/FindPost/3804018

Jon Sasor [Cakewalk]
there's a known issue for some users updating from BandLab Assistant version 3.3 to the new one, 4.0. If you download the new version separately, it should install without issue. You can find it here.

Yeah, found it. I was originally searching for Export problems, and found nothing on the topic that seemed relevant. 

 Just as I figured..... I can't get a direct upload to Bandlab either because both Cakewalk and the Bandlab Assistant runs off the Default Browser which in my case is Microsoft Edge which isn't supported by Bandlab.com and extremely unpredictable with any browser other then Google Chrome.
 But hey, no biggie, that's not a deal breaker, and hopefully these little things will all get sorted out soon enough.
 
 I've never been a fan of Chrome, not because I think it's crappy, simply because I was never familiar with it and never bothered to experiment with learning how to use multiple browsers..
 And now even with my Android based Samsung Galaxy, Edge is my first choice browser for integrating EVERYTHING in my entire home and office network together.
 And considering all the amazing things Bandlab.com does, I think it's a herculean achievement to get a cloud based DAW to run at all, it's certainly the first reason I've ever found worth installing Chrome as a secondary browser on my Windows computer.
 It really does blow my mind that I'm actually jamming and collaborating with artists working solely from a smartphone.
 I never thought I'd live to see the day when I could work on a mix I made in my studio anywhere I have cell phone service..
 
 But considering Edge is so tightly woven and integrated into Windows OS, ALL MY SOFTWARE has ALWAYS USED Microsoft browsers for updates and upgrades thru what ever browser Windows is currently supporting at the time it.  It never made sense to me to add more stuff to my system that could go wrong and to use another browser as my choice for default when all my software doesn't.
 
And so Bandlab.com get to use Chrome on my computer all by itself and I'll just let Edge handle all the other crap. :o)