Chambertin, you're in the wrong forum..lol..
But I'll try helping..
When you say indentations, it makes me think something/someone brushed up against your Pothos, bending its leaves, finally causing the leaf to die.
To detect mites, place a white sheet of paper under leaves..tap leaves over paper..Tap different leaves. Check sheet..if your plant has mites, you'll find tiny, various colored bugs on paper. Depending on your eye sight, you should be able to see mites on paper...if you have a magnfying glass that'll work,..
Also, mites build fine webbs. Check leaves, (over and under,) and stems.
If possible, spray leaves w/soap and 2-4 drops of dish soap. If you can't use soap, use plain water. Or better yet, take to a sink and hose off..I realize this would be difficult in an office...good luck Toni

Sorry, Chambertin, my error..I have 3 windows opened, and thought u were in Fragrant plants..LOL..Toni