Hello SSA9,
Thanks for posting in the PayPal community forums!
If you have sent yourself an invoice and are trying to pay it, our security system may have detected this and removed the ability to pay as a guest. This is as intended.
Your customers may not have this problem when receiving an invoice. If they do have a PayPal account, they can log into it to make a payment. If they don't, they should be able to pay as a guest.
I hope this helps!
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