Though this entry is notated with the symbol for an unspecified vowel, ⟨V⟩, in this case it does not mean the vowel is indeterminate. Rather, both*li- and*la- existed in opposition and became conflated to various degrees in the descendants, such that it is most parsimonious to unify them under one headword. The same is the case for*bV-.
Bravmann, Meïr Max (1977), “Expressions based on the nounyawm- ‘day’”, inStudies in Semitic Philology (Studies in Semitic Languages and Linguistics; 6), Leiden: E. J. Brill,→ISBN, page390