Whenever I use an "only on release" slider on a mobile device, it never sends a message on an actual release. It seems that mobile on-release action differs from the desktop on-release.
- create an on release slider
- run chrome -> inspect -> choose "responsive" or one of the mobile devices
- grab a slider and release it
N.B. The only way to get a message generated on a mobile device is to click on a slider without dragging it.