Changing setting for mass expiry gives 404 error

I want to change my settings for mass expiry, as some plans do not seem to be properly expiring (they are unpublished plans, do i need to publish first?) Ok answered my own question there, i republished the plans that were not expiring properly, and they expired just fine then i unpublished them.

Meanwhile, when i try to save the setting, it gives me a 404 category not found error. in paid subscriptions/settings/save

Any idea why that is happening?

That seams like a very odd error to be receiving. That would be Joomlas language key JGLOBAL_CATEGORY_NOT_FOUND and is for saving something without a category in Joomlas content component and a few other core components. I've no idea why it'd be happening in CBSubs settings. It's possible CBSubs settings are being cut short due to too many inputs. What is the value of "max_input_vars" and "post_max_size" within System > System Information > PHP Information?