Sorry Martin - I don’t see any fixes for ‘Beat Calculator’ listed (i.e. its reinstatement); I only see fixes for the Tap Tempo tool.
Lets be clear, ‘Tap Tempo’ and ‘Beat Calculator’ are SEPARATE tools/functions, with separate uses (well, they were in C12). Please refer to the huge, old (locked) thread for use cases/further info.
(I see you also posted the same ‘fixed in 13.0.20’ info at the end there too…! It is not fixed sadly)
[SOLVED] Beat Calculator Gone? - Cubase - Steinberg Forums