To add on to this: The Saris H3 does not support Resistance Mode which may explain some of the earlier confusion in this thread. Only Erg and Standard mode are available for this trainer. I use the same one and was wondering why it wasn’t available, contacted support and confirmed this to be the case.
Sounds like you figured it out with slope mode 
Also, if you did your ramp test while the trainer was behaving funny, it would be wise to retest now that you’ve figured it out. Also, seeing that you went 10 W over on what should be a pretty difficult workout possibly suggests your FTP is higher than what it’s currently set at