Using reference model 5700. Freesync is working normally in all other games and applications.
In CS:GO, with freesync off there is normal tearing as you would expect. When I enable freesync it is clearly enabled, because instead of tearing being randomly distributed, it is concentrated at the bottom of the screen. So there is no tearing in the top 3/4 of the screen, and constant tearing in the bottom 1/4.
The attached phone camera video has been slowed down to 50% to make it easier to see. In the second half of the video you can see the top portion screen has no tearing.
I'm using the in-game framerate limiter to limit FPS to well within the freesync range. It's definitely working as my monitor's OSD shows the refresh rate changing to match the FPS. It's just not fully working.
You should use a FPS limiter according to hetz valure of your monitor. For example, you can use FRTC. For example, if your monitor is 75 hertz, FPS limit should be set to 70 (ie less than 75). Briefly, FreeSync does not work when FPS value by the game is higher than the monitor hertz value.
The conditions for FreeSync to work properly must be met. The FPS value must be between the FreeSync range hertz values. Decrease the FPS limit for the game and reduce it according to your monitor's hertz (so game hertz). High FPS is as effective as you can see it.
Excuse me. However, you did not specify FreeSync range and the hertz setting of the game. For this reason, I again mentioned important things. CS-GO game usually gives high FPS. I think that's why you're having trouble.