This feature is a lifesaver for fediverse. It allows you to see from a general perspective, reduces confusion and creates a more organized forum environment. Thank you to everyone who has already used this feature and I highly recommend everyone to use it.
FYI: There’s currently an open issue with crossposting on instances using the 0.19.4 lemmy ui.
In a nutshell, the post submission page reloads after it retrieves the community to crosspost to, so everything but the selected community is wiped out.