For contrast, try a WordPress.com site that isn't atomic, it works as expected.
#user-report #2842911-zen
@spencerberry Could you please add screenshots or a short GIF video to demonstrate? It helps set the context — we can see the Gutenberg UI and determine lots of important details.
Browser / OS version info also helps.
It's possible this is related to recent Gutenberg updates on WordPress.com. Worth also testing on a self-hosted WP site with latest version of the Gutenberg plugin.

I tested with Firefox 74.0.1 on macOS with an Atomic site and couldn't find the Gutenberg option for making uppercase text.
I do see the control on a Simple site (same browser):

@spencerberry Tracked this down to the CoBlocks plugin — the Uppercase tool isn't from core Gutenberg, though it is a suggested change: https://github.com/WordPress/gutenberg/issues/20801
@Automattic/ajax FYI.
I can also replicate the issue in my local site with/without Gutenberg plugin, and I opened an issue in CoBlocks repo. https://github.com/godaddy-wordpress/coblocks/issues/1488
While testing 8.1 I encountered this issue on simple sites on both 8.0 and 8.1
Noting that this is closed on CoBlocks now: godaddy-wordpress/coblocks#1488
Waiting plugin update on dotcom to fix the issue.
Most helpful comment
I can also replicate the issue in my local site with/without Gutenberg plugin, and I opened an issue in CoBlocks repo. https://github.com/godaddy-wordpress/coblocks/issues/1488