We're currently aware of an issue where the Watteam POWERBEAT Dual pedals will only transmit half power in Zwift.
Two-sided power pedals work by transmitting the power of each foot, but Zwift can only pair with one power source, so dual-sided power pedals need their values artificially doubled in Zwift. This doubling process is a design change that has to be done on our end.
Until this change this is made, these pedals won't be compatible with Zwift. We're exploring the feasibility of doubling the power now, and we will update this post and our hardware page with changes.