EGR tech help

When in a workout for example
135w at 90rpm i can achieve this.
Same w/o then asks 135w at 65 rpm standing, i have to spin back up to 90 to achieve the wattage, at 65 rpm the watts are no were near the 135 Can’t seem to be able to match the wattage with the workout cadence
kickr snap big chainring

Having similar sporadic issues Kickr Snap 2017. All on ANT+. Using controllable mode for trainer but taking power readings from Garmin Vector3 pedals. ERG mode is not working well this winter when it was great all last “indoor” season. Something has changed!