Steps to reproduce:
Precondition: you have discovered LLDs with graph prototypes on a host

1. Open Data collection -> Host -> LLD
2. Open Graph prototypes for one of the discovered LLDs
3. Open Graph prototype's edit form
4. Click preview

Result:
"No permissions to reffered object or it does not exist!" is displayed

See video:

Expected:
Preview should work similar as for regular graph prototypes.