Andrew, Mike Ware's original Simple Cyanotype comes in three contrast variants depending upon the amount of Ammonia used in the synthesis - high contrast (exposure scale ~1.8, pH ~8), medium contrast (exposure scale ~ 2.3, pH ~6) and low contrast (exposure scale ~ 2.7, pH ~2.7). The high contrast variant has substantially more Ammonia (and consequently higher pH) than the other two. Intermeidate exposure scales can be handled by appropriately mixing the high and low contrast sensitisers. And with neutral water development instead of the usual acidic water development, the high contrast version can work with exposure scale ~1.3.
Now, the alternative process that you have used to make the sensitiser gives you, I suspect, the low contrast variant as it uses Ammonium Citrate (stoichiometrically synthesised from Citric Acid and Ammonium Carbonate) and doesn't have the excess of Ammonia needed for the high contrast version. That's why
Mike Ware wrote "this version lacks the range of exposure scale control" and gave it a different name - "Mike's Cyanotype". It's not surprising that you had to use a negative with higher density range to get an acceptable print from your sensitiser. You may want to check pH of your sensitiser to confirm.