Changing gravity causes sv_gravity to change rapidly

I set sv_gravity to 400, and when I did, sv_gravity began freaking the FUCK out and spammed the console and chatbox with


sv_gravity changed to 400.00
sv_gravity changed to 4.00
sv_gravity changed to 400.00
sv_gravity changed to 4.00
sv_gravity changed to 400.00
sv_gravity changed to 4.00

and went on forever without stopping.

I restarted my singleplayer and sv_gravity was set to 0.00 for some reason, so I set it to 600.00 (default) and then it did the same thing:


sv_gravity changed to 400.00
sv_gravity changed to 4.00
sv_gravity changed to 400.00
sv_gravity changed to 4.00
sv_gravity changed to 400.00
sv_gravity changed to 4.00

with the same gravity option before restart.

What the fuck is causing this/is this and how do I stop it