When running the exposed password report in Bitwarden (on the web), it seems to run forever without completing.
Looking at the JavaScript console, I see that requests to the HIBP API (looking up hashes of passwords) fails with CORS sameorigin errors.
The failed requests were to https://api.pwnedpasswords.com/range/{range}
I 've just tested this and was unable to reproduce the issue. In a vault with about 150 login items, the Exposed Passwords Report completed in around 2 seconds (in Firefox).
Perhaps you may have been affected by a temporary glitch? Is the problem still occurring? If so, approximately how many items are in your vault?