1) The problem → Wix only allows fully formed absolute URLs in its builder and doesn't support data attributes.

2) Why is this important → You can not implement the modals opening code on plans.

3) What's your plan B → There is no work-around that I have found. It may be possible with Wix JS but I wasn't going to start down that road. I moved to Memberspace as they do allow absolute URLs.

4) Possible solutions we could build for you → Allow absolute URLs to open the various modal windows. This does seem to work for login forms but not for membership plans.