I dunno how you managed to do it before, but you do know you're basically admitted to licence violation in describing how you're working?
You need separate licences per person using the software. And it should be installed on their own PCs, not a centralised server.
A comment, thanks...you misspelled license. Anyway we have all the required licenses I was just trying to avoid installing 3 separate instances of the software, made sense to me and worked at one point
OK, before you start "correcting" people's spelling, you should perhaps be aware that not everyone lives in the US, and accordingly not all of us use the spelling quirks of your version of English. And it's just a dumb thing to do, anyhow.
OK, it's good you've got the licences.
It really seems like an odd thing to do. Would you install MS Word centrally on a server, rather than on each desktop? These things are called desktop apps for a reason, after all. But never mind.
The only thing I can think of is that each person used to have an individual file system mapping back to their own user-specific profile (like an equivalent of C:\Users\[user name]\AppData), and their CFB environment was being written there? I'd have no idea what needs setting up and where/how, TBH.
Do they not even get the "workspace in use [select a different one]" prompt?
Perhaps look at any log files you can find in your CFB dir (and CFB workspace, and CFB config) dirs, and see what error you get. I presume it's gonna be down to how you're basically trying to run the same instance of CFB multiple times. I'm fairly familiar with the CFB docs and am unaware of docs of how to set it up the way you want to run, but perhaps have a google about for Eclipse instructions of how to do same. It'll be the same for CFB.
Basically you're not running the app the way it was intended, so you've perhaps gotta expect "weirdness". Really: it's be better to just install it how it was intended, I reckon.