AJAX-Calendar Masks HTML-Tags in Tooltips after changing month

I got a problem with the AJAX Calendar Module.
When the page is loaded the Tool-Tips are displayed as they're should:



As soon I change the month, the HTML-Tags are displayed:



It looks like that the POST-Answer includes masked HTML-Tags:
Does somebody have any idea how I can change this?

Versions:

• JEM: 2.2.0
• AJAX-Calendar-Module: 2.2.0

Hi, I work with JEM 2.2.0 with ajax-calendar 2.2.0 and on Joomla 3.6.2. (with t3-purity).
I can't reproduce your problem.

Did you try with only the official templates, modules and plugins. Can it be, that there something makes an interference witch causes this problem?

EDIT:
I tried with the official template protostar too: I can't reproduce.
So the problem must be inside your configuration and not the ajax module.

I use a custom template generated by Themler. May this causes this issue. I tried to find the error, but I run out of ideas.
If you like you can have a look to the page. It's www.feuerkreis.ch - I think you'll understand the Page :D

EDIT: I agree that the problem may is caused by the template or another configuration. But I need some help to track down the issue.

I can't help, maybe someone else!

Don't know the answer but also noticed a problem with tooltipping with that module in a different template (tk_gen_free_ii).

Protostar + beez seems to be working fine, but maybe it happens due to bootstrap /jquery what's being loaded by the template in question.

Greetings,
Blue

I don't think that's en error of bootstrap nor any other CSS thing. Because the HTML-Code returned on GET is invalid. The HTML-Tags inside the Tooltips are masked. To explain the error better I have an example for that:
If I load the Page fresh the Tooltips are looking good. The HTML-Code also looks great.
Eg. 5th of October:
If I Switch to November and then Back to October the GET-Answer for the 5th of October catched by FireBug looks like that:
But what is messing up the HTML-Code? Any Idea how to figure that out?