NX 'Improper reference set' message when opening assembly

A message similar to below is displayed when opening assembly from Teamcenter into NX:

Reference Set changed
The following improper reference set was set to that found in the Teamcenter product structure:
[SOLID] on part: [Test123/A]
This may be because this reference set does not exist. It is possible that you incorrectly entered the reference set name when editing in Teamcenter.
NX would try to reset it with the Reference Sets listed in the Assembly Load Options.
<<OK>>

It sounds like the assembly structure was modified in Structure Manager in Teamcenter. In Structure Manager, users can set reference sets for components in the structure...and the [SOLID] reference set was applied to this component.

However, when the assembly is opened in NX, it was found that the [SOLID] reference set does not exist in this part, so NX used a reference set from the NX Assembly Load Options. This is not a failure, merely an informational message letting you know what reference set had been applied.

Once the assembly is opened in NX and a correct or existing (ie. MODEL) reference set is applied to this component and the assembly is re-saved, you should no longer receive this message since the component will now be written to the structure with a correct (existing) reference set.

Alternatively, in Structure Manager, the Reference Set for this component can be modified to a reference set that exists in the part and re-saved.