When I need to copy a OTP password, I would click on the 1Password chrome extension, quickly type in the first few characters of the site to filter it instantly, click on the result in the list, and click on copy next to OTP.
What happens when I try to paste is that nothing from 1Password was copied into my pasteboard, but instead my previous clipboard from a different app was pasted.
I would try multiple times quickly, and it would fail every time.
However, when I wait 5 seconds before clicking copy on my OTP password, it would work.
1Password Version: 7.3.2
Extension Version: 184.108.40.206
OS Version: 10.15.3
Sync Type: Not Provided