(Firefox) Dataflow - error messages on save & close depending on the dataflow type

Hi,

We are experiencing very buggy behaviour when saving & closing a dataflow.

Existing dataflows that have been edited:  error message is typically "there is a newer version of the dataflow"
 - not true

 - it is not possible to navigate out of this error message loop

 - when we close the window as a last resort, we can see that the changes are preserved when we op the dataflow in a new window.

New dataflows:  "can't save dataflow - a dataflow with this name already exists in this workspace."
 - not true

 - it is not possible to navigate out of this error message loop

 - when we close the window as a last resort, we see the newly created dataflow when we open the workspace in a new window.

So far this behaviour is true for 2 users, both with PPU lisences in Premium workspaces. These two users are using Firefox to work with dataflows.
*Update - it looks like this error is limited to Firefox.