When using tppos with yaw and pitch the yaw value you input is not the same as the yaw you are teleported to.

EXAMPLE:

Entering /tppos 0 64 0 90 180..

..will teleport you to 0 64 0 -90 80

ANOTHER EXAMPLE:

Entering /tppos 0 64 0 -10 180..

..will teleport you to 0 64 0 170 80

180 is either added or subtracted from the yaw.