Is it possible that you have a filter applied to the portfolio view?

Echoing what @Lyndsy-Denk said, we set them up in Admin Console according to their Adobe ID.  If they do not own one, part of the process on their side will be to establish one.  Unless your IT chooses to federate external users this is the other way to get users into Admin Console.

We use Okta internally but external users are not authenticated through it.  Adobe Admin console is set up so that it will allow Adobe IDs for external users.  You have to add them to the system and provision them for the products.

We have some external vendors who have access to Workfront.  In Adobe Admin Console we have internal users set up with a Federated ID, all external users should be using an Adobe ID.  

I would consider building an issue report grouped by project

My client only works Monday-Wednesady. Any client dependent tasks need to programmed to be due on in office days Have you experimented with the Schedule setting?  I don't have any specific advise to offer other than it's there, sorry!    

I agree with @skyehansen - it seems like a bad idea to set up someone this way but it is technically possible.

If you are trying to search the content of the PDF I agree with @Madalyn_Destafney that this is not possible within Workfront

Yes you are correct, once the 100000 number sequence runs out it will be 200000 and on

I am 99% certain that the original person retains the same permissions - even if someone has been delegated ownership it should not mean that the original assignee has anything removed.  I would love to be proven wrong though!