Some componets are not rendered

[metricmind]

After the layout files, BOM, etc. are imported, most of components show up, but not all.
Interestingly, the ones that don't show up are identical to those that do, This is annoying, but
fixable - you right click on the spot where a component is suppose top be, select "Hidden Component List"
from the sub-menu and either use pre-defined one. (BTW, any idea why this could happen?)

However, some empty spots where a component is suppose to be displayed cannot be fixed
as above - right click on them shows "Component" menu selection grayed out (attached example).
as if such component does not exist in BOM or not in some input data. What's wrong?