In Muse CC 2018.00 the following problems with Menu creation were present:
Are these issues resolved in the Muse CC2018.1 update?
Your descriptions are way to unspecific and general for a valid answer.
I tried to test as far as possible, what I think, you are talking about, using an older version of Muse and the new one, and all works as expected in both versions.
Some of your issues aren’t reproducible due to lack of information:
So finally you have 2 strategies to receive a valid answer: