Hard to say if this is a feature or a bug but it has been reported a couple times. If you have copied a takeoff to your clipboard then open a new tab your clipboard will be empty. If you have two tabs open you can copy takeoff from Tab A and Tab B and then past The same data on each tab. I cant copy on tab A and have the clipboard paste that onto tab B. Tab B has it's own clipboard info.
This might explain it better:
https://youtu.be/MbTXjPhCX1k
Internal reporting on behalf of customer P. Hatch
Thanks for reporting. The browser tabs do keep track of their own "clipboard" currently. We'll dig into how to fix this. It's a little tricky since it's not actually copying to the true OS clipboard for the section data (otherwise it would be a huge JSON data object when you paste into another app such as notepad, which might not be all bad). I'm sure there is some work-around to solve this, though. It gets a little more tricky when it's copying data between projects, etc. but should be possible still.