Changing individual text character fill colour only breaks / removes individual kerning

Very odd bug.

Just had my carefully kerned type ruined by After effects when I changed individual character colours manually.

Any idea why this would happen?

I am pasting in hex values in the properties panel fill box or character panel

Some real work needs doing to get the type engine functioning correctly to avoid this sort of thing.

I can work around it with animators and it is sporadic. one of of 4 of the same characters moved.