Trying to understand a Grammarly correction.

I have two sentences in a paper, shown below; the only difference between the two sentences is one word. Grammarly shows a correction in the second sentence, to put a comma after the word class to separate two independent clauses, but not in the first sentence. I would like to understand the correction or if it is an error from Grammarly.

1. We will not review this instruction in class and solutions are not provided in the workbook.
2. We will not review this instruction in class and full solutions are not provided in the workbook.