ELO calculation error

Despite winning multiple games of catan and being rank 1, I have received 0 ELO points. I think there is a bug in the system and I have attempted to explain why this should never happen.
Based on the ELO formula shared on the website, if a player wins the game (i.e. has rank 1), then he/she should always have a positive ELO (>0). There has to be a very big gap in previous ELO scores between players in a game for the formula to generate a 0 (even when rounding numbers)
For example:
A: 1000
B: 500
If A wins, the ELO should be 0.43 (perhaps rounded to 0)However, this is a huge gap between previous ELO's which is unexpected among matched players. Hence a rank 1 player should have at least +1 as an ELO because 0.43 +0.43 = 0.86 = rounds to 1 (assuming player C also has a 500 ELO)