Can be tested out in the QAGame project. I’ve tested this in Editor. Besides the erratic behavior already logged in UE-33361, SetHapticsByValue stops vibrating after 3-4 seconds. Works as expected, i.e. continuous Vibration, on the Vive Controllers.
Still not working in 4.15. On the Vive it works fine.
Still not working in 4.17.2
I wonder if this question might be related. I wasn’t sure, given that I encoutered this with the Valve Index controller, but perhaps as a work-around you could try calling SetHapticsByValue without any 0 amplitude calls following it.
Don’t know the cause, but found a simple workaround (UE 4.26).
Touch controller will stop vibrating after 3 or so seconds only if the amplitude stays the same. This can be easily prevented pulsating your amplitude a bit (not noticeable to user) Make Pulsating Value does the job.
IF you’re using OpenXR plugin, every SetHapticsByValue needs to be preceded by another SetHapticsByValue with frequency and amplitude set to 0. The amplitude being the same does not matter.
Interesting that your work-around is to precede every call with a setHapticsByValue of 0, whereas mine was to find a way around a frequency of 0 being sent AFTER. (worth noting) I haven’t had a chance to try your suggestion yet.
huh, weird 
Well, OpenXR really messes with VR stuff in 4.26.