Inconsistent draft mode behaviour when deployed to Vercel - some paths get 404 without hitting server, others work as expected - Help

I have draft mode working 100% correctly on my local development environment but when my project is deployed to Vercel only some paths work, others return 404. I've reviewed my code several times to ensure that there are no implementation differences between the working and nonworking paths and I'm pretty confident that I'm doing things consistently for every path. The logs on Vercel show the draft mode working requests make it to the application server but the paths that bounce with a 404 don't ever get logged so it looks like Vercel is serving them out of cache. Any ideas or pointers as to what I might be doing incorrectly would be greatly appreciated.

Hi - thanks for the intro and pointer to the 404 resource. I've gone through the listed debugging tips and unfortunately I don't have any more insight into the unexpected behaviour exhibited.

error codes - the 404 is not the white screen
deployment exists - check (the rest of the site works fine)
deployment output - all good, the file being requested wouldn't be in the output anyway, as it should only be accessible in draft mode..
project config - nothing obvious, local build works 100%, some draft mode paths work when deployed to Vercel
domain config / permissions - not applicable - the site is otherwise fine

I'm still stumped as to why the draft mode bypass works for some paths but not others on Vercel, when they all work locally..

Hi - thanks for the intro and pointer to the 404 resource. I've gone through the listed debugging tips and unfortunately I don't have any more insight into the unexpected behaviour exhibited.

error codes - the 404 is not the white screen
deployment exists - check (the rest of the site works fine)
deployment output - all good, the file being requested wouldn't be in the output anyway, as it should only be accessible in draft mode..
project config - nothing obvious, local build works 100%, some draft mode paths work when deployed to Vercel
domain config / permissions - not applicable - the site is otherwise fine

I'm still stumped as to why the draft mode bypass works for some paths but not others on Vercel, when they all work locally..