ILS reception question

Anybody ever seen intermittent ILS localizer reception during multiple
missed approaches?
What causes that?

Was doing ILS localizer and back course approaches at McNary (Salem) last
night in solid IMC. That was a blast, until the third approach. We hit the
intersection at the right altitude, but couldn't get a solid enough needle
reading to complete the approach.

That's kind of a rush, when you lose radio navigation and you're in the
middle of a freakin' cloud. Seattle Center vectored us to VFR and all was
fine, but my instructor said she'd seen that happen at that particular
approach maybe a half dozen times, in as many airplanes. We've had NO
trouble with reception in that particular aircraft anywhere else, so it
looks like a transmission problem. What causes that, to whom can we report
it who will take it seriously, and is this common?

The flight home was pure Kodak. Vectored us to 6,000 feet which was the
overcast top and found outselves right on top of that layer with another
layer over us, and the setting sun right in between.

-c