This one has me baffled. I've got a membership contribution page that works just fine with paypal standard payments (membership is processed and everything ends up correct, no problems.) It also has a pay later option. This works in so far as a pending transaction and membership is created. It does not, however, show the pay later instructions at any point to the user. It does not send any email from the contribution page, I think it should. When you manually enter payment then it will send a receipt.
I'm stuck for things to look for. I can't find any errors in any drupal logs or the civiCRM log file that look remotely relevant. There is no custom code being used anywhere, everything is straight up configuration of civiCRM. There is no customization of email templates. The only thing I've done that is unusual is this used to be a civiCRM installation on Joomla that has now been moved to Drupal. I thought the pay later instructions were being displayed correctly when I fist did the transfer to Drupal, but maybe I saw things that were not there, not sure. I've added more extensive instructions since then and they don't show. The same instructions for pay later do show on event bookings (I've used the same text copy and paste.) Pay later works as expected on the events and sends emails and everything.
The civiCRM version currently running is 4.7.2 after just upgrading from 4.7.1 - there was no change with this upgrade.
Any ideas on where to look next? Do I need to turn on debugging and stat looking for things that way? Is there an obvious answer I've overlooked? I welcome all ideas.