I don’t know if this is new but I’ve never had the problem before.
In LayOut 2018 models are reloaded automatically each time the file is modified, which is very distracting and annoying. Every time I switch to LO I have to wait a second or two for it to be responsive (it is in my muscle memory to hit Ctrl+S every time I switch focus away from a program).
Previously LO has never done this to me. The model has never been reloaded into LO without me doing it.
Can this annoyance be disabled?