"Config" Specifier Does not Work Properly in 5.4+

In 5.4+, the Save/Load Config code requires the config name specified in the UCLASS to include either “Editor” or “User”, otherwise it doesn’t save/load properly.

Example

/* The parameters and actions for the Module Creator */
UCLASS(MinimalAPI, config = OseroSuitePerProjectSettings, PerObjectConfig)
class UOS_MDC_Settings : public UObject
{
	GENERATED_BODY()
  ...
}

In this code, the Config name is OseroSuitePerProjectSettings, so 5.4+ does not recognise it properly.

/* The parameters and actions for the Module Creator */
UCLASS(MinimalAPI, config = OseroSuitePerProjectEditorSettings, PerObjectConfig)
class UOS_MDC_Settings : public UObject
{
	GENERATED_BODY()
  ...
}

In this second example, the Config name is OseroSuitePerProjectEditorSettings and contains Editor, so in 5.4+ it works correctly.

Reference

Credit for the answer goes to Hyanier here:

5.4 Config not saving correctlyEpic Developer Community Forums