I encountered this issue the other day when searching for some translation in a reference TM in Studio 2024 SR1:
The copy & paste functions work just fine if I open a TM and click the Source/Target field right away.
However, if I click any TU after making a search or even after opening a TM, these function don't work any more in Source & Target fields, but I can copy & paste text in TUs.
Now, to get what is required, I can only: make a search and type the result I need elsewhere (which is inconvenient) OR make a search, copy & paste the result I need, close and re-open the TM and make another search (which is very time-consuming).
I tried some Google search on this matter but found nothing useful.
This issue doesn't exist in Studio 2017 (that I previously used), any advice on how to fix it is appreciated.
