Inivisble Sidearm during Spectate Mode Bug

I noticed another player's sidearm was invisible whilst I was in Spectate mode, and he/she was shooting. When I click to spectate someone else and then come back, the sidearm could then be seen. See below:



PC Specs:

CPU: i7 4790k
GPU: GTX 970 4GB
RAM: 32GB DDR3 @ 1866mhz
HDD: Samsung 840 SSD

Have noticed as well. For some reason when people switch to secondaries it breaks the animation and the observer sees nothing in their hands.