Hello @goodereader
Thank you for reaching out to us, we are here to help.
We have seen the error you have reported before, and we are aware this is caused by the YITH subscriptions plugin. This plugin is currently not supported by our plugin. The YITH subscriptions plugin tries to add PCP compatibility, but maybe have an issue with our most recent update(s).
This is not something that we can fix from our end, and you might want to try contacting the YITH developer to see if they can help you resolve this issue. Our plugin is only developed for and tested with the WooCommerce subscriptions plugin. If you require an immediate solution for this, we can only advise you to switch to the WooCommerce subscriptions plugin.
Please let us know if you have any further questions for us.
Kind regards,
Joost