Same issue here. Causes a 500 error on the site.
Here’s some log details, should anyone want to try to diagnose:
Fatal error: Uncaught ArgumentCountError: Too few arguments to function
CS_REST_BaseSerialiser::__construct(), 0 passed in
/usr/home/thebrewrom/public_html/ablecosmetics.com/wp-content/plugins/forms-for-campaign-monitor/createsend-php/class/base_classes.php
on line 193 and exactly 1 expected in
/usr/home/thebrewrom/public_html/ablecosmetics.com/wp-content/plugins/forms-for-campaign-monitor/createsend-php/class/serialisation.php:23
Stack trace: #0
/usr/home/thebrewrom/public_html/ablecosmetics.com/wp-content/plugins/forms-for-campaign-monitor/createsend-php/class/base_classes.php(193):
CS_REST_BaseSerialiser->__construct() #1
/usr/home/thebrewrom/public_html/ablecosmetics.com/wp-content/plugins/forms-for-campaign-monitor/forms/core/CampaignMonitor.php(38):
CS_REST_Wrapper_Base->refresh_token() #2
/usr/home/thebrewrom/public_html/ablecosmetics.com/wp-content/plugins/forms-for-campaign-monitor/forms/core/Application.php(139):
forms\core\CampaignMonitor->refresh_token(Array) #3
/usr/home/thebrewrom/public_html/ablecosmetics.c in
/usr/home/thebrewrom/public_html/ablecosmetics.com/wp-content/plugins/forms-for-campaign-monitor/createsend-php/class/serialisation.php
on line 23
