On the source Pi Node-red editor:
CTRL E, "all flows", Copy to clipboard - "Nodes exported to clipboard".
On the target Pi Node-red editor:
CTRL i, CTRL v - nothing.
Note It works with each flow on the source machine individually.
Also I just tested again after reinstalling Node-red and creating two simple flows, it happily paste them on the other Pi, but the opposite direction, 7 flows, failed.
I have tried pasting the JSON into notepad, recopying to the clipboard. It makes no difference.
Maybe it's bad characters somewhere in one of my flows, but it doesn't say "Invalid JSON", it just ignores the paste.
Suppose I'll have to construct a bunch of flows.json files to try and track it down.
This is a PC with WIndows 10.
The issue shows up on Firefox and Edge. Not sure about incognito mode but Edge has no privacy related settings or plugins enabled.
I don't see how it can be a browser related problem Steve, a single flow copies and pastes OK, "all flows" are copied to the clipboard and will paste into a web page text area - Google translate for instance - but not into Node-red.
the right click paste menu item is system/OS driven so if it is greyed out then the OS believes there is no compatible data in its clipboard.
I know there is nothing in node-red that operates clipboard copy in node-red by simply opening the import dialog and certainly nothing that checks the clipboard format then "clears" the clipboard before showing you the right click menu.
What happens if you export full flow, paste into notepad, TRY to paste into this other node-red (non working one) then try paste again into another notepad. Does the OS clipboard still have the JSON?
What do you see if you press win + v? Is the JSON still on the clipboard?
After I turned on history, it shows the JSON. Still on the clipboard.
Note that after seeing the problem I copied all the flows one by one from one Pi to another.
Then I deleted .node-red and ran the installation script on the first and tried to paste them back again in a single export.
So it's not confined to a single target Pi, it seems to be specific to that JSON export.