Login redirect glitching to Custom Links

We have TML installed.

When subscribers log in, they should get directed to /member-portal/ where we have custom pages for them. Attempts to load those pages without being logged in gets them bumped to the login form.

On Sunday we created 10,000 subscriber accounts, on Monday we sent emails to 10,000 members inviting them to log in to view the member-portal. An immediate success, with much interaction with the content and functionality we built there.

Except … there was a trickle of enquiries/complaints/etc where a member had entered the login details we sent them, and instead of being redirected to the member-portal pages they were left facing a page with three links: Dashboard, Profile, and Log Out.

We don’t have the Custom Links option of TML turned on.

When we try to recreate the experience using the login credentials we emailed them on Monday, we get redirected to the member-portal pages as intended. At least, in all the half-dozen times we’ve done that. Maybe we’ve just been lucky.

When we tell the member with the failed login to try logging out and logging in again, they get redirected successfully. Well, for the dozen or so cases so far. Maybe we’ve just been lucky.

So, out of many hundreds of logins, there’s been maybe a dozen or two glitches.

It looks like a heisenbug glitch with a low random frequency.

I don’t understand why the Custom Links page was appearing at all, since we left that option turned off.

I just turned it on, simply so I can delete those two default links and insert a new custom link to /member-portal/, and when I do a subscriber login I still get redirected to the intended /member-portal/ page. The custom links page doesn’t appear even with the option turned on (but I don’t want it to appear, since we’re using TML option to redirect logins to /member-portal/). At least, that’s the behaviour in the 2 or 3 subscriber logins I’ve just done. Maybe I’ve just been lucky. Fingers are crossed that if the glitch trips again they’ll get the custom links for subscribers, as I’ve set up, and not the custom links for some other account level.

So … why the heisenglitch? Any advice?

I do not envy you tracking down this bug.