I2C debugger, as the name suggests, is just a debugger. So, if it works with the debugger connected, it should work without the debugger connected as well. If it doesn't, it may be a problem in Proteus, especially since it works fine in real hardware.
I think there's a problem in Proteus' simulation of hardware I2C without the debugger connected. I remember I had the same problem as well. But, everything worked fine with software I2C or in hardware I2C with debugger connected.