Hello, I have been suffering from this problem for some times and it seems alright now when disabling the above settings, do i need to keep them disabled or try enabling them back?
if I understand your issue correctly, you are using Fill & Sign tool of Adobe Reader DC and while filling a form its getting stuck in the middle.
To know better what exactly causing trouble here, we'd like you to check the following-
1- Check and see if your application is up-to-date or not? Open Adobe Reader>Help>Check for update.
2- Open a different form and check the same thing with that, does it hung up while filling it too? If yes, then-
Navigate to Reader>Edit>Preferences>Security (Enhanced)>disable "Protected Mode at Startup" and "Enhanced Security">OK>Reboot Reader>Reopen PDF form and check back.
Note: Changing the above security settings could pose security risks. We suggest you to turn it back On once you are done with testing.