It's been noted in a couple of other threads that libreoffice applications do not always group together as defined in a users ~/.fluxbox/apps file.
With xprop, the class name for libreoffice will be along the lines of:
WM_CLASS(STRING) = "libreoffice", "libreoffice-calc"
which is normally what would be used in the ~/.fluxbox/apps file.
However, while tracking down another issue with libreoffice, I found that when launched, libreoffice actually uses the class names "soffice" and "Soffice" before switching to the libreoffice class strings identified by xprop.
So i changed my ~/.fluxbox/apps file to:
[group] (workspace=[current])
[app] (name=soffice) (class=Soffice)
[app] (name=libreoffice) (class=libreoffice-writer)
[app] (name=libreoffice) (class=libreoffice-calc)
[Deco] {0x67f}
[Maximized] {yes}
[end]
which is working to group the libreoffice documents and spreadsheets. The libreoffice class designations are no longer needed, but I left them in.
I haven't tested this yet to see if distinctions can be made with soffice-writer, soffice-impress etc ...
Yes. It was changed (once again) some time ago. Thankfully this time it's finally coherent amongst the programs in the suite so they can be grouped all together again as in older versions. I hope this change lasts for a good while.