Hi, Samuel.
In our forums we keep our threads focused on just one issue at a time to ensure we fully answer each of your questions/issues. Please keep this in mind for the future and start a new thread for your additional questions from this thread. Thanks for your understanding, and I’ll answer only your first question.
Does your first issue still happen if you switch to Twenty Sixteen theme and all non-Modern Tribe plugins are deactivated?
If yes, please provide a video screen capture demonstrating the issue so I can better understand it and try to reproduce it.
Thank you.