Thanks for linking, I could not find the duplicate despite searching.

I would suggest that if this is by design / a technical limitation, that the GUI can be instead be improved so that it does not act contrary to expectations

Using the "Select new contents for the blueprint" when editing an existing blueprint does not respect the "Save blueprint". In other words, the blueprint is changed as soon as the new content of the blueprint is selected, even if user never clicks Save blueprint and instead clicks the X after ...

For some reason my 4x4 splitter balancer (with 3 input lanes used and 3 output lanes used) was not giving full output despite full input.
Issue seems to be fixed when a downstream splitter is removed and replaced

https://imgur.com/w3qKTlh

Save attached (still has the balancer with 3 inputs and 4 ...