To reproduce:
- Type 1234 (or any string) in the composer.
 - Type an @ before the 1234 (to get 
@1234) - Select someone from the dropdown.
 - Hit backspace 2 or 3 times
 - Select the person from the dropdown again.
 - The beginning of the 1234 gets deleted.
 
To reproduce:
@1234)Is this still reproducible @Ellibereth?
Yes it’s still reproducible, I tried to fix it months ago. But wasn’t happy with my solution. I should give it another go.
This is fixed, I fixed some time in the last year with another positioning bug.