I was distracted by the very small size of your symbol {your symbol is tiny 0,0666 cm not even 2 px in size), but I think I found the cause of the problem.
Your symbols are Dynamic symbols. If you change that in the Symbol options to Static the numbers will appear.
I can recreate the problem in 2024, but it works fine in the 2023 version.
Looks like a bug in the 28.5 version.
This seems to only happen with jpeg export, png export looks fine and jpeg export for screens works too.
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