I used only mamp pro. I have over 30 sites working al fine on MAMP Pro. On real hosting I dont know. I only upload sites to a real hosting to finalyse the websites. So in the last stage.
The problem was on the homepage of both websites I updated from PB3 to 4. After I experienced this I closed it.
New addons also gave weird behavior. Every time "error, invalid addon settings".
The addon hardly responds to a command.
I couldn't exit the page in a normal way. completly stuck. Only option was "back to administrator".
I build Joomla based sites for about 8 years now. Imo it should make any difference whetever the site is used on a local machine or on a live environment. The protocols are the same.
Something with the update from BP 3 to 4 is wrong. I have build a fresh site using PB4 and did not have any issues so far.
Fun part is that for that site I didn't even create a database.. Forgot that in my hurry, but it worked.
Best and easiest is to get a copy of my backup and see so devs can see for themselve. It's the PB3 backup before you update to 4. Then you guys have all information.