PopUp Pro does not save

Hi,
I am unable to create a new popup. After entering all information, then clicking save ends up in an infinite cycle of the save spinner. After refreshing, or any other action, no popups are created. I have looked at all the forums, even possible conflicts with ACF, even tried disabling many plugins, reinstalling Popup Pro, nothing works. Popup Pro gets stuck in the save spinner without saving anything.

Thank you