I use the Tickr X heart rate strap.
Their are occasions when on both indoor/virtual and outdoors cycles that my HRM gets stuck in a certain range.
It gets up to around 100/105bpm and tops out there, even though I know im pushing hard enough to be hitting about 180/190bpm.
Ive tried hard resets, making sure monitor is well positioned and that the contacts are moist.
It will do it around once a fortnight, and work perfectly well the other sessions.
Can anyone offer any other potential solutions to try?