caja as administrator

[Dominic Knight <dominicknight@gmx.com>]

I guess this is something I have done at this end but, although it
works fine as a normal user (right click and open new instance), when
trying to open any folder from Caja as administrator (right click on
folder in Caja, select open as administrator) I get the message:

"Please start Chromium as a normal user. If you need to run as root for
development, re-run with the - no-sandbox flag."

I wasn't aware of trying to run Chromium at all, it used to open a
separate instance of Caja with su privileges. Anyone else or something
I have done badly somewhere and forgotten about?

Debian Testing(Buster)
Mate 1.18.0
Caja 1.18.3

TIA,