Can't suspend when debugging using EDS12.1

I'm using a design created in Quartus 11. It runs from flash. It containts a NIOS II core.

In EDS 12.1, I get the problem that suspend (pause) doesn't work.

Steps to reproduce:

1. compile a simple C program

2. start debugger. Console says: Listening on port 6645 for connection from GDB: 59saccepted

3. press 'start'

4. after a little while, press 'suspend'

Problem:

the debugger quits. Console says: Connection from GDB closed. Leaving target processor running

Expected:

The debug halts, and allows to inspect stack, variables, etc.

When using EDS 11.1 or 12.0SP2, I can debug just fine. All works as expected.

I've got this problem on my PC, but my colleague sees the same.

Creating a new design in quartus 12.1 shows the same problems.

This is all on our custom board, using a USB blaster for JTAG.