fatal error C1083: Cannot open include file: 'f550011.h': No such file or directory

Has anyone got some ideas on this package build issue in DV. We have a custom NER (N550011) that fails to build. The compile log shows the following error:

n550011.c(28): fatal error C1083: Cannot open include file: 'f550011.h': No such file or directory

Diagnostics conducted so far:

1. The F550011 table exists in DV,
2. Table is accessible through UTB/DB.
3. The objects haven't changed for over a year (according to OMW)
4. The N550011 successfully compiles in OMW locally.
5. I have attempted to repopulate the F9870R / H table in DV using R98780R
6. Audited the OCMs,
7. Checked other items such as .INI settings (Include , Lib, Makedir, VS Studio version 2017).