"Yes, Independent of CMS "allow registration""

For the last week about 1 in 10 new users are only appearing in the joomla user table, not the Comprofiler table.

I can sync them, but we then do not collect the info from the CB fields.

There are no Joomla login modules published. Any ideas why this would happen?

www.thejungle.uk.net/index.php?option=com_comprofiler&task=registers&Itemid=2733&profiletype=jungle-explorer-club

Typically happens when something interrupts the registration process when the Joomla user object is validated and stored. Typically a 3rd party Joomla system or user plugin is easily capable of doing that. Another cause could be users registering outside of CB, but that shouldn't be possible unless it's a 3rd party extension since CBs system plugin in Extensions > Plugins blocks access to Joomlas users component. How are you handling profiles types? Looks like maybe CB Profile Pro. I suppose it's possible that could be causing issues before CB user is stored. Without you having a way of reliably causing the issue I can't really say what else could be doing that as there isn't a way to debug it properly without being able to reproduce the issue.

I've been using CB Profile Pro for several years now without a problem and haven't installed any new plugins for over 6 months, only updates.

I have had a couple of customer's show me a page not found error after registration. An auto action should have sent them to a thank you page but it sounds like their registration didn't get that far. The only think I can think of is that I've noticed a slow response at times on the site.

I've tried myself to replicate it several times but I register without problem.

Auto action thank you page? Do you've a redirect auto action configured? If so what trigger are you using.

onAfterUserRegistration

That's too early to redirect. I recommend using onAfterSaveUserRegistration, which is triggered just before the registration complete message is output.