Need to set ISO manually with Godox TT350 flash?

I bought this compact external flash recently and started using it at a party in bounce mode.  It's a good thing I checked the shots right away, as they were seriously underexposed on my GX7.   Aimed straight ahead, the Godox was OK.

I stopped using the Godox, and just went back to using the camera's built-in flash (in bounce mode, pushing the flash back with my finger).  The photos taken that way were fine.

When I got home, I played around with it on both a GX7 and GX8.  I realized that even though the camera was set to auto ISO, the ISO actually stayed at 200 with the Godox, even in bounce mode in a dim room.  By contrast, using the weak built-in flash, the camera would set ISO to 2000 or whatever was needed to get a well-exposed shot.

I found that once I set ISO in the camera to 1600, the Godox exposure was accurate.

Is there some setting to change in the Godox that can let the auto ISO feature in the camera work properly?    Is this problem unique to Godox?  Does auto ISO adjust properly with other brands of external flash?

The Godox flash is working properly. It adheres to the Olympus flash system - TT350o (O for Olympus). The Olympus flash system defaults to the base ISO of 200 when ISO is set to auto. I think the assumption is that most photographers would rather not use an unnecessary high ISO if they're using flash to light the scene.  I personally prefer this to the Panasonic system.

Don't forget the Godox has flash compensation on the unit +/-3, which I often use. However, once you've reached full power you'll have to change the ISO manually to increase your exposure.

Unfortunately, I'm not aware of a way to re-configure this.

Cafe Racer.

Try flash adjust in body and on the flash. +2/3ev on the flash usually can get satisfactory result on  my GX7 and GX85.

Use flash, is originally to add enough light artificially to keep ISO low (in the old days, to keep shutter speed fast and now, keep image clean). Of course we can use manual ISO if needed.

When we bounce, will indeed reduce the effectiveness of the original expected output of the flash. For a lot of reasons it can under expose. Use flash adj to fine tune the output for the result.

My 2 cents.