I am experiencing problems with opening, moving, deleting, etc. of files when this file is being previewed in Directory Opus. Often this can be remedies by clicking try again (sometimes that needs to be preceded by clicking on another file so that one is previewed). When I turn off the preview, this issue occurs very seldom (at least I cannot reproduce it). Not an enormous problem, but it is annoying.
I work with version 12.28.
This issue occurs with all kind of files: zip, MS Word, PDF, etc. The strange thing is that it does not occur always.
Those are all things which involve 3rd party viewers when displayed in the preview pane. Viewers are not meant to lock files, but sometimes they do anyway. (PDF viewers are especially bad for this.)
The ActiveX + Preview + Office + Web plugin (which acts as a proxy/intermediate for third party viewers designer for File Explorer etc.) has a per-viewer option to open temporary copies of files instead of opening the real files directly. That can help with some viewers. You can configure it under Preferences / Viewer / Plugin.
(Of course, the file is going to be locked briefly when it is being opened, whether that's to load it into the viewer or to make a temporary copy of it. There will always be a small window of time where the file will be in use, but it should be small, unless the file is huge or antivirus is chewing on it for a long time.)