So don’t use the deb file method.
Install the latest driver for your 1080Ti using the latest driver runfile installer for it obtained from:
It should be a version like 381.09 or higher.
If you have properly installed CUDA 8 from the latest runfile installer (CUDA 8.0.61) then the only thing you should need to do is update your driver with the driver runfile installer.
This is not a bug per se. A given video card is not supported by all drivers that were ever created in the past. It is only supported by drivers that were released after the video card was released. In the case of CUDA 8.0.61, it was released before 1080Ti became available. So you have to use a newer driver than the one that comes with the 8.0.61 installer.
To avoid the Ubuntu login loop, you should follow the same method you previously found to avoid that, when you install a new driver.