Thank you, Nayeem. It is practically impossible that it works properly from your end as we have accessed it from various platforms and browsers and the behaviour has been abnormal. Anyhow, since your last visit, my SysAdmin identified the problem and its solution. I am reporting it here just in case it helps somebody else too. Though your plugin already calls Bootstrap and theoretically this should take over, we had to re-activate Bootstrap (v5) specifically on our Page. This has sorted out the problem. So now, after having found and solved the incompatibility with queries and the reason for inconsistent expand/collapse behaviour of the Tree Directory, we are ready to work more with using your software. See for yourself. If ok with you, I will remove your temp Admin rights.
Back to 2nd original question: Whilst on the subject of ArchivePage, is there a way that the individual file size is shown in the returned “Attached Files” list? I think that it is important for the prospective downloader to know in advance the individual file size before embarking into the specific download.