I work for/with/teach pro colorists, mostly based in Resolve. So I'm both in Resolve most days, and also on the LGG and BlackMagic forums daily. Resolve ain't no magic bullet, there's a long list of people who've had issues with most of the builds of 18. Very similar to Adobe forums, sadly.
But ... it is easier to test an upgrade in a CC app than Resolve, thankfully.
Install the new major version ... making sure the "remove prior versions" option is NOT checked!
For some reason, even if your CC app prefs are set with that unchecked, new major version install boxes ALWAYS have that checked, so beware!
Next, on launch of the new major version, dump all cache files.
And ... create a NEW project, then use the MediaBrowser panel to navigate to an older project. IMPORT the assets of that project. Which leaves that project totally as-was in the old version.
Now ... test the new version with your media/effects/workflow. If it works, fine.
If not, just open the prior one and get back to work.