Right. That would definitely cause the issues you’re experiencing.
A few things to keep in mind:
1) Any buttons that you generated on the test site should be regenerated on the live site to ensure they’re generated with the correct domain in the custom=”” attribute.
2) Anyone who signed up for a recurring subscription with a button that had the wrong domain in the custom=”” may still have that wrong domain associated with the subscription on PayPal’s end. To the best of my knowledge, when you use a PayPal button to create a subscription, PayPal stores all the settings of that button on their servers and uses those settings for future messages related to that subscription. So, if someone signed up with a button that had an incorrect custom=”” attribute, the only way to fix it is to have them cancel that subscription and create a new one using the correct button.
3) The s2Member upgrade/downgrade process that occurs with a Billing Modification form works by canceling the previous subscription and creating a new one. So, if an existing member used a bad button to sign up, but then upgrades using a good button (i.e., a button with a correct custom=”” attribute), the old (bad) subscription profile will be canceled and replaced with a new (good) subscription profile.
I’m fairly certain that the custom=”” attribute in a signup button/form overrides whatever is in the Custom Value field on their profile, but it certainly wouldn’t hurt to update that field on their profiles with the correct value.