The reader could become confused about what is being said here. The writer wrote that Jeroboam was called to the assembly, when he had already indicated that Jeroboam was there, and implied that he was Israel’s spokesman.
There are two ways in which this circumstance can be understood. First, it might be a reference to another and larger assembly of Israel that included more than simply the leading men. In this manner, there was a realization on the part of people who had not known before that Jeroboam had returned from Egypt and was available to lead Israel.
The more likely explanation is that this is another interruption of the sequential narrative of the writer to ensure that the reader knows that not only were the ten tribes separated but Jeroboam had been made their king. Thus, the Lord’s judgment on Solomon and his descendants was fulfilled by all of the tribes of Israel removed from the dynasty of David, except for Judah.
20 And when all Israel heard that Jeroboam had returned, they sent and called him to the assembly and made him king over all Israel. There was none that followed the house of David but the tribe of Judah only.