What happened to the Old Chinese coda -p of 拉 in Cantonese?
The qu4 去  tone class in Middle Chinese is generally understood to derive from an OC suffix –s.  Sagart regards the whole class as deriving from this process (Roots of OC, p. 131). This results in word pairs of plain root and root + s that in Middle Chinese and later differ by tone.
If the –s is applied to a root that ends in a stop, it seems to efface that stop in later developments.  Sagart, citing Baxter, gives these examples (p. 54):

nei4 內  *nups &gt; nwojH  ‘inside’, compare na4 納  *nup &gt; nop  ‘to put in’
dui4 對  *tups &gt; twojH  ‘to answer’, compare da2 答  *tup &gt; top  ‘to respond’

In Cantonese, in both these cases, the final stop has been retained in the second (unsuffixed) word, but has disappeared in the first.  (In Mandarin you don’t see it anywhere, because all final stops are gone.)
The –s suffix seems to have had a variety of functions.  Often it seems to form exoactive or causative verbs – as well as Sagart, Schuessler discusses this at length in the introduction to his etymological dictionary.
Could the Cantonese form of 拉 be the reflex of a word with this suffix, which caused the final stop to be lost?