REST api Filter fail that doesn't make sense.

[CantStopTheFlow]

This is probably more for the StackExchange bin, but I'll fire it here and see what happens.

I have a filter that fails when it's like this:

     ?$filter=SiteId eq 50 and Year_x002d_MonthId eq 92

but not this:

     ?$filter=Year_x002d_MonthId eq 92 and SiteId eq 50

It complains that the first one causes the possibility of a large list issue of too many items returned, but the second one doesn't, despite the identical syntax, just switched.

Site(Id) is a lookup column to a Sites (locations in the world) list with 100 items.

YearMonth(Id) is a lookup column to a YearMonth list with 400 items. (Every year and month combo for a decade.)

This same filter is used for multiple list, MetricA, MetricB, MetricC, which all have the requirement to record a Site & YearMonth. What would be the cause of needing to swap the location of the filter parameters to make this work, for only one of the lists, and not all three?

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I don't have the ability to mark anything as answered, as my browser always blocks it. So, tell me how to fix that, and I'll mark that as an answer, too.