Galaxy S6 timer and stopwatch affected by motion/proximity

[Android Central Question]

My Galaxy S6 timer and stopwatch functions of the clock app are affected by moving the phone (e.g. just setting it down) and proximity (holding my hand close to the phone). They will start or stop unexpectedly, and sometimes will switch between timer and stopwatch modes (this happened with proximity. I have been all over the settings and see nothing that can help this, and have not found anything helpful in Internet searches. Basically, I just want the timer/stopwatch to start when I tell it to, and stop when I tell it to, and not otherwise. Does anyone have any suggestions?
Thank you.