Hi. I received your files and checked them. You are right. What seems to be happening is the following:
1- In each separate file you are changing the visibility settings of the rebars to be unobscured and solid.
2- When you linked file B in file A the rebars lose this setting. I actually binded the link, went into group editing mode, and then checked the settings. The two checkboxes were cleared.
It seems that this is an error that autodesk needs to to take a look at unless we both are missing something. I will try to find a workaround while keeping the file linked. Otherwise, your best option would be either to bind, or create as a group and load, or use phases instead.
I have taken a look at the files and AJA14's comments, and have found that this was recently submitted to our development team by another user. I have added this thread to that report. At this time the development team has not identified a time frame on when we can expect to see this addressed. Unfortunately I do not have a better workaround other than binding the link or maybe Copy/Monitoring the floor and adding reinforcement native to the host file. I am sorry for the trouble that this causes to your workflow, and hope that we see something implemented soon.