Could some one explain why sigma seems to drop out in some verb due to an intervocalic ejection with compensatory lengthening of the remaining vowels but not others. The mi verbs seems problematic.
Richard Ross
Sihler, “New Comparative Grammar of Greel and Latin”, 1995, has a bit of a discussion on this topic.
Intervocalic σ lost originally was then reestablished at a later point.
Section 172b. has,
“In certain morphological categories, -σ- was reestablished intervocalically by levelling.”
This section specifically mentions the second-person singular forms of -μι verbs:
“In 2sg. foms like τίθεσαι and ἐτίθεσο -σ- is restored”