Dan. initial [θl] became [fl]; [θl-] > [fl-]

Dan. initial [θl] became [fl]; [θl-] > [fl-]
According to the Comparative Tables initial [θl] became [fl] (PE19/21), but there are no attested examples of this change in The Etymologies. A similar change occurred in Noldorin at least part of the time.

Related

Phonetic Rule Elements

[θl-] > [fl-] ✧ PE19/21 (thl- > fl-); PE19/21 (thl- > fl-)