I am also having this issue with BotW and Launchbox. Cemu 1.26.1, stock settings.
The game launches from Cemu's menu just fine, but fails to launch from Launchbox after loading cached pipelines. All my other Cemu games load fine, EXCEPT Axiom Verge, which stalls on load from Launchbox but works fine from Cemu.
"useRDTSC = false" doesn't seem to do anything.
Also tested on Cemu 1.20, same results.