This occurs with me too on PC [Steam, no controller]. I'd like to add, however, that the same (or markedly similar) issue is present when you get the Spray ability with BD-1 In that case, the workaround (holding both the default keybind and your desired rebound key at the same time) does not seem to work for me beyond the first room of the tutorial, and I am unable to progress. (Edit²: that may actually be more related to the BD-1 visor softlock issue, my bad).
Edit: To expand, and clarify something that I haven't seen mentioned elsewhere in this thread: this issue is not limited to the tutorial if you use the workaround. Using the aforementioned workaround (holding both the default keybind and your desired rebound key at the same time), you can fire the blaster using your rebound key for the duration of the tutorial, but upon [unknown conditional ― perhaps moving between areas], the issue will re-occur and the workaround will need to be performed again (much like the need to re-toggle the Pull-Hold option on area traversal). However, the workaround does at least work reliably with the blaster stance, even if it makes it wildly impractical to use. In the case of BD-1's spray ability, this was enough to get me beyond the first tutorial room, but did not function for me on the second room (where you are tasked to return to the room where you fought the two Goroccos and use the spray again). It appears only using the default bindings in their entirety is a way to avoid this issue long-term, which is not a remotely feasible solution, especially given the state of the default keyboard bindings here.
