We are a small team, ~5 users. 99.9% of oC access done via Linux desktop clients, ranging from version 1.8 to 2.2.2. I occasionally use Android client, but almost never did an upload from it (recently).
Locked files vary, sometimes files opened with vim, some LibreOffice documents… Sadly we realize a file is locked long time after last usage, so it’s even hard to remember what has been done to it to cause this condition.