New Calc functions in release 7.x: Non-volatile RAND and RANDBETWEEN RAND.NV and RANDBETWEEN.NV see bug#127831 https://wiki.documentfoundation.org/ReleaseNotes/7.0#Calc
IMO also would be fine a place in the help explaining about what 'volatile' means for calc functions, and even better with a list of that functions. A good link awsering user questions.
Olivier Hallot committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/help/commit/7e39048579d0049c19299c1e31a2878e21e218ec tdf#132586 Add RAND.NV() and RANDBETWEEN.NV()
Olivier Hallot committed a patch related to this issue. It has been pushed to "libreoffice-7-0": https://git.libreoffice.org/help/commit/ec1bf858a6efae449cf6c1bbf237e6cb1c358a26 tdf#132586 Add RAND.NV() and RANDBETWEEN.NV()