First thing to check -- your AE version. If it isn't at le4ast 11.0.4, you need to update it.
current version is 22.214.171.124
This only happens in After Effects, not Encore or Premier.
Change anything on your machine lately? Graphics card? Drivers?
Also: try importing by dragging footage items directly from their OS folders onto the project pane. It might work.
And of course, you should do the dead-simple remedial steps like turning off the machine.
Tried dragging directly from the OS folders. That did work. ( why didn't i think of that?)
I have not had any changes from last month. i was working on a project in April and everything was normal.
Re-booting has not resolved the issue, I re-boot daily, and this started on Tuesday.
At least i can get started on my work now.