Thank you so much Wolfgang, it solved it! I guess this is new as with LMTX from last week(s) it wasn’t required.
Le 2 juin 2024 à 14:38 +0200, Wolfgang Schuster <wolfgang.schuster.lists@gmail.com>, a écrit :
Alex schrieb am 02.06.2024 um 14:08:
Hi everyone,

I’m facing an error with the latest LMTX with my custom font
definition: Math error: parameter 'subshiftdown' with id 49 in style 0
is not set

\usetypescriptfile[alegreya_libertinus]
\setupbodyfont[alegreya-light,ss,10pt]

\starttext

Hello

\startformula \Gamma_1 \stopformula

\stoptext

Add

    features=math\mathsizesuffix

to \definefontfamily when you set the math font. By default all font
(including monospace and math) get "features=default".

Wolfgang