username with dot and hyphen not recognized.

[sherwin14]

Everything is working until i entered a username with dot and hyphen.

@user.pretty - not working
@user-pretty - not working
@user_pretty - working (but only @user turned to green in ui)

here is my regex. "(@[a-zA-Z0-9._-]{2,50}\b)"

i tried debugging the list here is the result:
[@user.pretty, @user-pretty, @user_pretty]

in ui here is result:

every mentions should be in color green..

Can you help me with this?