Bimonthly utility_meter won't allow more than 28 days offset

I’m trying to set up a utility_meter sensor to track my water usage and align it to my water bill. My water utility company bills bimonthly in mid Feb, April, June, Aug, Oct, and Dec. I’ve created this:

    source: sensor.water_usage_per_day
    cycle: bimonthly
      days: 49

but it doesn’t pass the HA configuration checker, the checker cites that the offset days cannot be more than 28! I originally had it at days: 18 which made it reset at July 18th, September 18th, etc. That’s 31 days off so I need an offset of 49 or -13. The utility_meter doesn’t like negative values nor values over 28.

Just for completeness, I tried the quarterly and yearly options and they also have this 28 day / non-negative value limitation. I feel like this may be an oversight since these broader time-ranges should allow a reset anywhere within the time-range.