CrossStudio for ARM doesn't detect target debugger

The last few days I have been experiencing connection difficulties between CrossStudio and the SEGGER J-Link Ultra V4.00 that I'm using.

Everything started with randomly disconnecting the J-Link when trying to debug code, but worked just fine when downloading the release version of the program to the board. The disconnections increased in freq up until now, that the J-Link is not even detected by CrossStudio, therefore neither debugging nor flashing the board with the Download option (shortcut: CTRL+T, L).
Things I've tried:

• Using another J-Link (from a workmate) that is fully functional. Same behaviour.
• Updating the firmware of the J-Link. Same behaviour.
• Changing the USB port used to connect the J-Link to my workstation. Same behaviour.
• Changing the USB cable. Same behaviour.
• Making sure the device is properly detected by the OS. (lsusb -v). In addition to be recognized, all the info given by the command looks good, but still same behaviour.

So I think I've completely discarded all J-Link SW and HW possibilities, isolating something wrong with the IDE as the only possibility.
I've search the web too, but the most similar I've found is with another debugger, 8 years ago, and the blame went to the debugger manufacturer, therefore not very helpful. Any ideas?

EDIT: I've also tried to generate a new project and run some irrelevant code just to discard anything project settings related (although my settings haven changed in months). Same behaviour.