[NSFW] PhP Mail error

Hi there,
I’m using Form Maker 1.13.47.
I’ve created 2 forms with emails submission to the same email address (mine).
The first form runs as expected but the second cannot send any email.

When debugging this issue with WP Mail Catcher, here is what I get:
Triggered from:/home/wsite/public_html/wp-content/plugins/form-maker/framework/WDW_FM_Library.php
On line: 5008
Sent at: 13 December 2020 21:43:29 (1607895809)
Errors: Could not instantiate mail function.

Thanks in advance for your help.
Francois