Hi @mahfuzul
Thanks for your patience. This is a challenging issue and I wanted to be sure I’ve thoroughly investigated it for you before we wrote back ??
To further investigate the issue at our end, I have enabled the error_log using wp-config.php with the OptinMonster plugin version 2.6.9 and WordPress version 5.9 plus tried adding the OptinMonster inline campaign shortcode but the error log shows zero error for me: https://a.supportally.com/E6y14s
As you mentioned, I also looked at the inline-campaign-shortcode-modal.php and there is no syntax error on line number 14.
Could it be possible for you to reinstall the OptinMonster plugin and check for the error?
If the error still persists, To further troubleshoot the issue, Could it be possible for you to run the compatibility test? Try disabling all the plugins keep the OptinMonster active and activate plugins one by one to see the error.
Also, what is the PHP version you are running?
We really want to get to the core of the issue you are facing ??
Looking forward to hearing from you!
Regards