This bug is occurring for me on the Snapshot for 19w11b. I've played on Survival and Creative mode and they will not calm down unless I exit the game and restart. Even in peaceful mode on Creative, they will not calm down.
This has happened in my server for 18w11a. The workaround for now is to do /gamerule doFireTick False and manually put out the fire. You can turn it back on after the fire is controlled.
This bug is occurring for me on the Snapshot for 19w11b. I've played on Survival and Creative mode and they will not calm down unless I exit the game and restart. Even in peaceful mode on Creative, they will not calm down.