Well if you search for bcolz on the forums you will find many import error reports, even if you discount the ones that are due to pip. Even though it is in the environment.yaml, sometimes it doesn‘t get installed. Sometimes it does but cannot be loaded,sometimes it has to be uninstalled and installed together with different numpy versions, there are non systematic errors here. And I have had that problem myself on ubuntu and conda. I have the feeling it also depends on the order of installation and so sometimes works if you manually install it after the environment setup. I cannot reliably reproduce the issues. This is one of the many threads regarding bcolz errors:
Some also experience problems after git pull/ conda env updates while it was working before, again there seem to be specific numpy version requirements or incompatibilities.
These reports go back to 2017 and include paperspace setups. And yes, sometimes it is just user error, such as not activating the env etc.
But just by statistical occurance, this seems to be the module with the most installation error reports (probably followed by cv2…)