XML-API REST-Parking requires hitting Dial (or Select) twice to Pickup a call from the parking lot

I have Sangoma S705 phones and use the endpoint manager in FreePBX 15 to configure them. As of this point in time, all modules etc are current and up to date.

We use the XML-API REST-Parking app and after a recent change I made it now requires TWO clicks on the Dial (or Select) button to pick up a call. Previously it only took one. This of course confuses our users.

Few more notes:

On the first click, the Line button Goes Green, so it's doing something.

On the first click, there is NO activity in /var/log/asterisk/full

There is at least one other person that has seen this. See https://community.freepbx.org/t/have-to-press-dial-twice-to-retrieve-parked-call/78115

This change in behaviour seems to be related to updated Sangoma S705 firmware.

I previously was running  firmware 1.63, but upgraded to 1.67 (in the endpoint firmware manager). WIth that older firmware, I did not have this issue. I have tested all the versions from 1.63 -> 1.67, and all versions greater than 1.64 have this problem, and 1.63 and 1.64 work fine.

I don't know if this is related or not, but I also recently switched my SIP transport from UDP to TLS. I suspect TLS is less frequently used, thus people might not have stumbled into this if it's an issue related to both the firmware version and use of TLS.

I marked this as Minor as we do have a workaround, but anyone else running into this probably won't figure out that it takes two clicks...