Ambient light sensor and speaker issues after repair

Hi guys. Just replaced the front facing camera/sensors cable on my iPhone 6. Everything is working except for the sensor light: the screen doesn't turn off during calls when the phone is next to my ear, and audio messages like in telegram aren't routed to the front speaker.

I'm afraid the problem is that there's no way to keep the sensor in a fixed position while mounting all the rest: the mic has adhesive and a small pin that keeps it in place, the speaker has that little protruding oval-shaped plastic that fits into the foam on the back of the screen, the camera has the small transparent plastic casing... the light sensor is just there, beneath all the rest, but I'm afraid even half a millimeter off its perfect position makes it not working.

Auto-brightness works fine and sometimes, when covering the sensor hole with my hand, the screen does turn off, but it doesn't come back on when removing the hand.

I've reopened the phone three times now, trying to fix this, but to no avail.

Any suggestions ?

Thanks a lot!