Please use a release build of MaxScale. As Xpand nodes apparently were going down when the MaxScale assertion was hit, it may be that the assumption expressed with the assert does not hold in that context. In a release build the asserts are compiled out, and thus it would not be triggered. It is possible that a release build MaxScale would just work. It's also possible that it would crash, but that would provide additional information.

Debug builds should only be used if there is a particular reason for it.

We are using the SKY 2.0 dashboard to create our services. So we have no control over what maxscale gets set up for the service. Shouldn't the DEV service be equivalent to the PROD that is being offered to customers?