Two problems:

I have tried to send out emails via HTML and have for this reason changed the pre-filled emails.

HTML seems not to work for the Registration emails - can you confirm?

Even more challenging for me:

The "Link to open password reset form" is no longer showing the link.

I have cleared all caches and now even excluded the forum.

I have several times re-filled the email field and checked all information. 

All other dynamic content is created, but not the "Link to open password reset form"

The email I tested looks like this:
Twst - Registered user login - Link to open password reset form

Also formats seem no longer to work,

What can I do?

Thanks for your help