Issue with "mark as read"

[Faravid]

Hi,

First, thanks for making Fossamail, Thunderbird has needed some tech love for a long time, it has been painful especially with large boxes.

Anyways, I have had this problem for ages with Thunderbird and looks like it has transferred to Fossamail as well. I copied my settings folder from Thunderbird.

The issue is that I have 2 Gmail addresses and the other one of them doesn't automatically mark the messages read, I have to mark them read by using the right click menu.

Settings are perfectly identical with the other address (except for of course username, box name etc...).
Settings are also identical in about:config.

Any idea what might cause this? I've tried pretty much everything I can find online.

[Faravid]

Forgot to mention:
This issue happens ONLY in the grouped received mails view, not in the invidual email folders.