Hello Christine.
I think Chris is right about the Any. If there is a bug, it's in the compiler. We were always told that when the compiler got to "Object." it stopped looking at the statement, leaving it much like the DYNAMIC keyword. You're saying "trust me it'll be right at runtime". In this case the compiler can't tell what the dot notation returns so can't match it to the type of the function argument. IMHO, an Any is not necessarily a Long, so it should therefore fail the compilation.
It is interesting that you get a consistent number returned though, which does suggest something amiss somewhere..
FWIW since you're doing a point query you'd get microscopically better performance and the same solution as Chris's by using
of_testingnullarg( tab_2.tabpage_comp_info.dw_webcomp_info.GetItemNumber( i, "dormant" ) )
HTH, Paul