Joseph schrieb am 14.01.2020 um 22:58:
>
> Hello,
>
> With LMTX (MkIV is fine) characterspacing (I use frenchpunctuation) is 
> not applied sometimes (ie no spacing before colon for example) in some 
> parts of the text. Unfortunately so far I cannot provide a MWE so I am 
> wondering if there is a way to trace this to hopefully figure out what 
> the problem is.
>

You can enable tracing with

\enabletrackers[typesetters.spacing]

Wolfgang