There are three main channels for obtaining help with MNE software tools.
The MNE Forum is a good placed to go for both troubleshooting and general questions.
If you want to request new features or if you’re confident that you have found a bug, please create a new issue on the GitHub issues page. When reporting bugs, please try to replicate the bug with the MNE-Python sample data, and make every effort to simplify your example script to only the elements necessary to replicate the bug.
The Frequently Asked Questions (FAQ) page also has a few troubleshooting tips, and is a good source of general information too.