I have made sure this is the case for my setup and it is still not working. I posted a video in a response higher up in the thread to illustrate this. My pop-up settings allow Anaplan (screenshot attached).
We ran into a similar issue where mailto was not working in Chrome for PC, but appeared to be working in the MAC. I work on a PC the original Model Builder was on MAC.
There were two issues I found
1) CC and BCC fields formatted to Text/Mailto but were empty. I changed this to text and hardcoded to ""
2) Body of the email had either extra special characters or too many characters...this was done to try and create line breaks in the body. Special character seemed to be working on the MAC. I removed the extra spaces / special characters and this resolved this issue.
I did a argument by argument debug of this so I am pretty confident that these were apparent issues.