Use your finger, move the screen left or right or tilt your device, the screen will fluctuate
Actually i agree that MR Handys are a problem but not so much for this specific issue but for the fact that you cannot set them to run away from incidents. Considering the cost to repair one and the fact that most rooms have well equiped dwelers i would rather just keep my Handy's focusing on resource collection and ignore/run away from danger
The only solution I've found for this incredibly frustrating issue is to make sure that all my dwellers have enough health to survive any possible incident without needing any stimpaks. This means training up the endurance of every single one of them, as soon as they arrive, not upgrading any rooms unless necessary (workshops and empty storage/living quarters only), and making sure to heal them all back up to full health after any incidents, in case they get hit by another while wounded.
It's crazy how much I've had to do, just to deal with a UI issue. I can't ever assume I'll be able to use stimpaks mid-incident. Still getting invisible health bars, compounding the problem, but same solution - if they have enough health, and I don't upgrade the rooms they're in, it doesn't matter.
I suffer too. I found a solution, however. If you drag the camera slightly so you can see all of them from a slightly tilted view, they all separate enough to be healed.
If it doesn't work, I have no more suggestions.
Problem is, this works sometimes, but sometimes not. Sometimes even though they separate enough to see, the top one keeps getting selected anyhow, and while clicking like crazy at every possible angle, the bottom one dies. It's worth trying, but it isn't reliable.
Generally, when a fire or any other disaster breaks on the floor which my Cosworth (Mr. Handy) is located, the first thing i do is send him to another floor. He tries to extinguish or fight enemies, and cost to repair them is not cool.
So, since i just have 1 Mr. Handy, shooo! Go away from this floor Cosworth!! And just come back when things are finished and back to normal!!
By far my biggest problem is the vault door - I constantly have Mr Handy 4 Raiders/Deathclaws and my two guards all stacked up in the same corner - tilting and shifting helps a little, sometimes, but there are times when you get too much pile up and not enough time to wiggle and tilt and perform voodoo rituals to get to the dwellers. It would be great if they had a "Stimpak All" option or a medical Mr. Handy that would take care of that for me.
As far as moving Mr. Handy I'm at the coin cap all the time so I'm not concerned with his repair cost and appreciate the help he otherwise provides.