The following example is from Exodus 13:
The first two speaker labels correctly indicate that Moses and then the Israelites are speaking. But why is there not a label in verse 9 to indicate that Moses is speaking again?
By design.
Moses didn't stop speaking when he told them what their response should be to their children. He is still speaking as part of the entire double-quoted block.
But why is there not a label in verse 9 to indicate that Moses is speaking again?
Simply because at no point has he stopped speaking! The second speaker label is Moses speaking what the Israelites will speak in the future.
I realise that from the narrative standpoint. Exodus 14:5 has two speakers labels, but 13:8 does not. In Exodus 16:6 there is a double label for Moses and Aaron and in verse 8 when it is only Moses that speaks, there is another label placed there just for him. Based on these examples, I would expect two labels in 13:8, one for Moses, one for the Israelites, and then another label just for Moses when he resumes as the sole speaker. I do realise that there is a difference between 13:8 and the other passages I have mentioned: in the first, the Israelites are not actually speaking whereas in the others two speakers actually are (at the same time). Yet to the extent that 13:8 is labelled with the Israelites as speakers, it seems inconsistent to me the way it is.
Based on these examples, I would expect two labels in 13:8, one for Moses, one for the Israelites, and then another label just for Moses when he resumes as the sole speaker.
Moses is the sole speaker throughout. Two labels would imply that both are speaking the words at the same time. What matters is that a Search returns the correct result for Moses speaking between Ex 13:3 and 13:16, including the 'reported speech' at v8 and v14-15. The latter is shown by a search for <LDHB = Reported Speech (Lv. 2)>.
{Speaker <Person Israelites (the Exodus)>} OR {Speaker <Person A Son>} also shows the reported speech.
