How strange about Paypal not working when it's fairly easy.
The only thing I can imagine as I experienced it myself is if you both tried to pay as "friends and family", for certain accounts this option is not available and will in fact mark an error to the client. She should try to make a "Pay for Goods and Services" or "Generate an invoice".
In my case, I can accept payments this two ways, but not the first one, it throws an error to my clients and makes it unable for them to pay me if they choose "family and friends", as well, it is illegal to pay for services this way to avoid fees, not to mention it is very difficult for clients to make a refund if something bad happens.
Other method is if she creates a paypal.me link and then you can pay, it is also like a normal purchase.
Or doing a proper invoice and requesting the payment (Basically, you giving her your paypal email and let her do the recepit with the contents and specifications of the service/product bought.
Did she bother into asking Paypal why she is the one not being able to accept payments, because if I were her I would be desperate since that could also mean that I may be in trouble with other clients that are unable to pay me and to me it is so weird that she insists into working on a comic when you can't pay her and there seems to be no other viable method either.
Not to mention she doesn't have an alternative like CashApp, Western Union, or the other methods you mentioned, as well, according to what you wrote she doesn't even sound desperate either.
I don't want to jump into conclussions but I'll be careful, some scammer artists do these thing of building trust and that "oh no biggie!" situations but later on these cost a lot or they cancel you on social media with "BUHUU I WORKED HARD AND THEY DON'T WANT TO PAY MEEE!".
So yeah, Insist on NOT moving forward with the series and avoid sending her scripts or anything whatsoever, her persistence is weird, and I say it as an experienced artist that works full time making comics.
Again, I don't want to jump into conclussions but it is also common that... the usual artists that do this are either art thiefs.. tracers or just con artists in general.