Intermittent problems with selecting construction geometry in sketchfor mating or creating relations

I've ran into this problem a couple of times and always found a
workaround, but I would rather address the problem that continue using
workaround.

Short version:
Sometimes I can't select construction geometry created in a sketch
even when I have the sketch set to "show".

Long version:
Scenario #1:

I am editing a sheet metal part with with holes created by extrude
cut. I wanted to replace the holes created by the Extrude Cut feature
with a Hole Wizard feature. I changed the circles in the sketch which
created the extrude cut to construction geometry. Then created a Hole
Wizard feature on the same surface, with the location points in hole
wizard coinciding with the circles in the sketch. It worked perfectly.
Second step was to create an alternate configuration with a different
hole type. So I suppress my Hole Wizard Feature create a new Hole
Wizard Feature, and repeat the steps above. However fo some reason I
cannot coincide the holes with the any construction geometry in the
sketch. I try and try again Hiding and showing the sketch for some
reason no matter what I do I can't create any relations to the sketch
construction geometry.

Scenario #2

I have a part to be brought into an assembly. The part needs to be
spaced at exactly 15" in an array but the part itself is slightly less
than 15". So when I created the part I added a construction geometry
15" box around the the part. I bring the part in and I mate one side
to another part using the construction line I created in the sketch.
This works perfectly. My next step is to mate the top edge using the
same method. For some reason Solidworks will not allow me to select
the construction geometry to create a mate.

I've been able to work around these problems and continue but I would
like to know why I can select construction geometry only
intermittently. If I create a simple part to test this issue I never
run into problems it only happens with more complicated parts.

Anyone have any idea what I'm doing wrong.