Creating a new newsgroup-account when clicking on a mailto-link

It seems that there is an annoying known bug in the portable version.
When I click on a mailto-link TB portable open as expected but then want to create a new account for newsgroups.
If I don't want to add this and cancel this process I'm not able to use the link in the way it is supposed to be.
I have to copy the link and manually add it to a new email window of TB removing mailto:.

Seems to me, that DDL isn't working right.

My system is Windows 10 Pro 64 bit.

I would really appreticate if this bug gets fixed because I don' t want to switch to the Desktop Version and it's registry flooding.