Is that happening with the code in your pastebin or is that from another version?
Have you tried it using the code from your pastebin?
If you are testing a different version then what version of bootstrap are you using because I believe older bootstrap removed the fixed positioning for smaller screens due to devices lack of support at the time.
As mentioned above if you have a live version then it would be best if we looked at that to test.
These are the reasons that fixed positioning is best avoided in most cases.