"File in use" AFx locks footage items on a harddrive

I'm guessing that it's related to the 'PDF compatibility' feature of illustrator files. On Windows machines Adobe have made PDF files 'write locked' when open. If I save the Illustrator file as not PDF compatible, the problem goes away (unfortunately, AE will no longer display the file). I believe Adobe have not implemented write locking on Mac or Linux - so why do so on Windows?

Build 15.11 same problem for me. I can't edit an Illustrator asset that was opened in AE. It worked in the previous version of AE. Even closing  the project and purging all memory and caches I still get error: -54 file locked messages in illustrator. It's costing me a lot of time to completely close and re-open AE every time I have to edit an asset.

I haven't seen this issue on my systems yet.

Can you describe a bit more what you're doing so I can try to recreate your process on my end and see if I can make it do the same thing?

Adobe AE CC 2017 is a dog.  Really stinks up the joint.

There are very few issues officially recognized as bugs, but there are a great many quirks in it that can make it virtually impossible for many people to use without long and painstaking diagnosis.   Interestingly, some people report no problems... but if you look at the long list of woes reported in this forum, you'll probably come to the conclusion that something is amiss.

My advice:  use an earlier version that actually WORKS.