I'm using After Effects CC 2017 and Premiere Pro CC 2017 - all up to date
Processor Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz, 3601 Mhz, 4 Core(s), 8 Logical Processor(s)
Adapter Description NVIDIA GeForce GTX 1080
I have been using dynamic link to import footage from Premiere to my AE project and it's been working fine up until today. I can import the footage into my project panel and view it, but I'm prevented from being able to drag it into a composition
Wiothout any details about your Premiere sequence and the footage used within nobody can tell you much. This could be as trivial as some odd audio track arrangement. Other than that start by flushing all relevant caches in both programs. Perhaps your disks are simply full or the caches corrupted, preventing preview rendering.
It would be a lot easier (and probably faster) to just copy and paste your footage from Premiere into AE.