I'm facing this too. I'd say about 20% of my clicks are "lost." They either disappear entirely or they cause mouse0 to be locked down, and I can click again to try to release it.
I noticed this happens with keyboard input too, e.g. when typing my character name - about 20% of keys were lost.
I'm playing in English (no IME) on Windows 7. I have a 4k display but run PoE at 1080p, in fullscreen. I've had Steam overlay enabled so far, but would be fine turning it off for now. Output log attached.
output_log.txt