Custom emails using the Reply-To address from configuation?

Your software
My Mautic version is: 4.2.1
My PHP version is: 7.4.3
My Database type and version is: MariaDB 15.1

Your problem
My problem is:
I’ve set up a few template emails for a colleague to use, for particular contacts who need a more personal approach. The idea is that my colleage can open a contact’s record, click “Send email”, use the “import the email from existing template” dropdown to load the email template and then tweak the email wording to suit that specific contact.

This all works okay, and the email sends fine, but we’ve noticed that the when the contacts reply, the replies are coming through to our general inbox (which we’d set as the default “email address to send mail from” in Mautic configuration), instead of going through to my colleague directly.

I’d set the template to use my colleague’s address as the From and Reply-To address.

The emails are being sent from my colleague’s address (as per the template), but Mautic is ignoring the Reply-To address in the template and using the default address from configuration instead.

Is there any way to prevent this happening? These are our most important contacts and my colleague wants to deal with their replies promptly.

These errors are showing in the log:

Steps I have tried to fix the problem:
Sent a custom email to myself and confirmed that, although the from address was the same as in the template, the Reply-To address was mautic’s default address.