Is it that the part is not loading, or just not displaying? When you open your assembly do you get a dialog listing parts that failed to load, or is there some other message reported?
What happens if you change your Assembly Load Options to load "As Saved"?
Select "Menu > Information > Assemblies > List Components". It should list the directory path for the file it failed to find: 2017_011_CV_V2b.prt. Is it the same directory as the assembly?
I suspect that the part you are failing to load is not saved with the assembly so:
1. Ensure that the part causing the warning message resides in the Assembly
2. Load the part causing the issue manually
3. Ensure that all the assembly nodes all the way from the part causing the issue all the way to the top node is loaded fully
4. Save the assembly with the top node as Work Part - this will save all the assembly nodes recorrding your part to truly be part of your assembly, should there have been a glitch somewhere during creation & first save.
This should reslove your issue.