Onboardees required to log out and back in to sign documents - is this a bug?

I wondered if the community can help with this issue, I have been unable to find anything in the documentation.

Currently, when an Onboardee logs into their account, they are able to complete forms and personal information without issue. However, the option for them to sign the documents does not appear unless they log out, and then log back in again.

Is this a known issue, or is there something in our onboarding setup that is causing this? Any information would be appreciated. This is in ONB2.