Sometimes, during the Child Creation process on SmartThings, weird issues can occur, causing duplicate child devices. When this happens the duplicate pair of devices will behave strangely. The only way I know to correct this is to remove the Parent device, and then manually re-add it, and configure it again via the ST Classic App. Afterwards, the children will be created again, and hopefully this time they will all behave correctly.
This only happens on SmartThings. It never happens on Hubitat.