Users not updating but getting error message

Hi there

If a user who is already on my list goes to this address:
https://markdeeksmusic.com/makemeapianolegend/

…they get the error message that they are already subscribed. However the form in question has the Update Existing User set to “YEs” in the Opt In Settings.

I have users who have expressed an interest in product A and I want them to express an interest in product B which is launching imminently. Therefore, as the new form at that URL has 2 new tags set to be added to a user, I want to allow current subscribers who don’t have those tags to have those tags added.

I have tried with users who have neither of the new tags, and users who have one of them but not the other, and in both cases they get the error message that they are already subscribed.

If you could help me fix this ASAP it would be much appreciated thank you.

The page I need help with: [log in to see the link]