This sort of symptom was discussed on this post: https://fmdev.filemaker.com/message/88035
Unfortunately, I don't think you'll learn anything from that post that you don't already know.
According to something I said back at that time, I was able to cancel the lock with a NewRecord script step, but this did not work for the original poster, so that might not help.
Good luck & best,
Edit: Clarification: In the other post, we were looking at this problem on OSX.
Well, at least I know I'm not alone and I will need a comparible workaround if I deploy to a OSX environment. Many thanks!