Base goal calories inconsistency

Runnerhasbeen

I've been logging on MFP for about a month. My weight loss target is set at 0.5kg per week, and my base calories were 1820. As I usually have quite a lot of calories left over (I "earn" quite a few from exercise), I decided to change my weight loss target to 0.75kg per week.
I did not make any other changes.
When I did this, my base goal calories dropped to 1200. I thought that sounded very low, so I changed my weight loss target back to 0.5kg.
Again, I made no other changes.
But my base goal calories, instead of going back to 1820, changed to 1460.
This seems very inconsistent to me.
Has this happened to anyone else?
I did raise it with technical support, but I received a generic reply (which I responded to) and haven't yet had a more specific response.