The 'include search directory property will truncate the specified path when any white space character is encountered.
Right click on Check Syntax and choose Properties.
Under Specify search directories for 'include, a user specifies "/da/test/directory1 | /eda/test/directory2"
When they run Synthesis or Check Syntax, the process fails because one of the 'include files is located in /eda/test/directory2 and the path was truncated after /eda/test/directory1.
Additionally, if this property only contains a white space (Space or Tab), the user receives the following warning message:
"WARNING:HDLCompilers:176 - Include directory does not exist"
If a space is added after the first directory, the subsequent directories are ignored.
To work around the issue, remove any white spaces from the path in the process property.
This issue has been resolved in ISE 8.1i sp1.
With ISE 8.1.01i and later, unneeded white space between paths in the process property will be ignored.