Keep riding! Fliiiight learns and gets more precise as you ride.
Tip: You can speed up this process. Vary your wheel speed during your warm-up interval. This gives Fliiiight more data points for its wheel model, so it can nail your first tough interval.
Gear up. ERG mode works best on Fliiiight if you stay in your highest, fastest gear (big front chain ring).
We do not recommend pairing a separate powermeter as the source of power in your training app, or using "power matching" features available in some apps. This can result in inferior ERG tracking.
If Fliiiight stops receiving new commands due to interruptions in connectivity, it will keep implementing the last command it received, until it reconnects. In some cases, the power reading will also stop updating. Troubleshoot interference. This is the most common cause of ERG tracking that becomes worse partway through your ride.
If the trainer is changing resistance, and tracking accurately at the low end, but stopping shy of creating enough resistance for your high intervals, make sure to gear up, and check the height of the magnets relative to your brake rim. If they're partially facing above the rim or partially facing the tire, they may not be able to create enough resistance. See more troubleshooting for Fliiiight is not creating enough resistance.
Check if your trainer is receiving commands from a different app. You can see the number of apps or devices you are connected to over Bluetooth based on the pattern of the status light. Close irrelevant apps, and if necessary put your device briefly into airplane mode to force them to disconnect.