Hi @AndyTake2
A chord can only be sus if the 3rd is missing.
D = D, F#, A = 1, 3, 5
With F# in the bass the chord has its 3rd so cannot be sus.
The 4 is now counted round to its equivalent of 11.
Hope that helps.
Cheers 
| Richard_close2u | JustinGuitar Official Guide & Moderator