UCCNC Version 1.2036, 2017 Screenset V1.06 and Hyplugin V1.00094 (ENABLED and Call startup both selected!)
Using the default screenset and hyplugin, I set the hyplugin SACT field to 20050 (recommended). Edit screenset to match. Spindle starts and I can control speed +/-
Wen I do the same in the 2017 screenset, spindle won't start (relay in VFD clicks).
Put 2017 screenset SACT field back to default 869 value, spindle starts, but field doesn't update (as expected).
2017 screenset SACT field at 869 value, update hyplugin SACT filed to 869, spindle starts, but field flickers at 3000 (minimum speed). I can increase / decrease speed, but SACT field is constant at 3000 (it flickers, as I think your screenset is writing there as well).
Happy for guidance in the errors of my ways
Gordon.