As you can see in the attached image, when writing from Quartus II, the USB-Blaster is not recognized anymore. The USB-Blaster was recognized fine for a few days, but yesterday it suddenly stopped being recognized. Immediately after rebooting the PC, the USB-Blaster is recognized. However, the Altera USB Blaster is always visible in Device Manager.
The version of Quartus I tested was 17.1.0 and 18.1.0. I have the same symptoms on two different computers(Windows10 64bit).