tbl_PIP_AllSites is more canonical and the column names are not SQL standard and need to be referenced as below.
SELECT pip.*, sites.[Prop Name],sites.[Site Name]
FROM tbl_PIP_InspectionMain AS pip
LEFT JOIN tbl_PIP_AllSites AS sites ON pip.[Prop ID] = sites.[Prop ID]
tbl_PIP_AllSites
is more canonical and the column names are not SQL standard and need to be referenced as below.