Syntax colour highlighting problem - not working on some of my systems

[Chris Green]

The eternal problem....

On just *some* of my several Linux systems colour syntax higlighting
isn't working.  It always used to work but I really can't see what I
might have changed on *some* systems to break it.

The systems and versions and 'working or not' are:-

    backup      xubuntu 22.10   vile 9.8w       colour OK
    bison       Android 11      vile 9.8w       colour OK
    caracal     Debian 10       vile 9.8        no colour syntax
    cheddar     Debian 10       vile 9.8t       colour OK
    esprimo     xubuntu 22.04   vile 9.8u       no colour syntax
    isbd        Ubuntu 20.04    vile 9.8t       colour OK
    odin        Debian 9        vile 9.8s       colour OK
    pimedia     Debian 11       vile 9.8u       colour OK
    t470        xubuntu 22.10   vile 9.8w       colour OK
    tsohost     very old        vile 9.8        no colour syntax

Since esprimo is my main desktop system it's a bit annoying that
syntax colouring isn't working there.

On all systems 'show-colors' in vile works fine, so they're all
*capable* of colour. The two systems showing just vile 9.8 are ones
where I have built vile myself, so they have pretty recent code.

All systems have the same .vilerc and it runs with no errors.  So they
all execute:-

    source filters.rc
    setv $autocolor-hook HighlightFilter
    setv $read-hook HighlightFilter
    set autocolor=500
    set bcolor=default

I'm stumped!  Can anyone point me at some way to diagnose what's
wrong? Could it (possibly) be something to do with built-in or
external filters?  If so, how do I tell whether vile was built with
'built-in' or not?

-- 
Chris Green