Hi Hans,
I noticed that with the recent LMTX version 2021.06.27 16:59 the hyphens do not show up correctly with lucidaot.
Here is a minimal example and the resulting PDF
\setupbodyfont[lucidaot,10pt]
\startTEXpage
c'est-à-dire
sous-ensemble
sous-préfet
\stopTEXpage
Best regards: Otared