New configuration is imported with incorrect order of properties

Thanks for the report. This appears to result from core changes in [#3230199], see the accompanying change record → . Features needs to sort the way core does. Relevant: #3229250: Add service to sort a config array the same way core does. → . The ideal would be that core exposed a service we could use. Other options seem to include (arranged roughly from most to least attractive):

• See whether this issue is addressed in Configuration Update Manager (which we already require) and, if so, use a service from that module.
• If not already fixed in Configuration Update Manager, or if fixed but not yet available in a service, address in that module.
• Introduce a dependency on Config Split (or some other module that provides a relevant solution). Not so good, as Config Split addresses a distinct set of use cases.

Of course, the ideal would be that core provided something we could rely on, so we don't need to recreate core's (potentially changing) config sort algorithm in various config modules. That could be, for example, an optional boolean $sort argument to a new ConfigInterfaceInterface::save() method or similar.

A possible interim step would be a soft dependency: use the config_split service, if present, to sort config before it's saved.