We recently stopped using our SIS due to continuing issues that weren't being addressed. We need to enroll students but we're having problems doing so as the system keeps saying that although the students are in the system, they cannot be placed in a class or they're not being recognized.
We do have SIS ID's in some of the classes and attached to some students, but the new students do not have an SIS ID since we stopped using the SIS. Would this make a difference? Can someone assist?
Do you have (or can you generate) spreadsheets of the users, courses, and enrollments?
It's quite possible to use the "SIS Upload" tool to manage users, courses, and enrollments even if you don't have an SIS. The critical thing to understand is that the "SIS_ID" is just the unique identifier for users and courses that will not change. In most institutions, it would be a student (or faculty/staff) ID number for users, and a course/section/term identifier for courses.
The SIS Import makes use of the SIS_ID field to match the users in the users and enrollment feed files, and to match the courses in the courses and enrollments feed files, so there must be an SIS ID in order for the process to recognize the person or course. You can go back and manually add an SIS_ID to users and courses which don't have one, and that will allow them to be managed by the SIS Import process.
There is some introductory information on formatting feed files in CSV format to be imported via the SIS Import tool at https://community.canvaslms.com/t5/Admin-Guide/How-do-I-format-CSV-text-files-for-uploading-SIS-data...
How are you trying to add the students when it says "they cannot be placed in a class or they're not being recognized"?
If you are trying to add them using their email address in the individual courses using the "Add People" button, the most common cause I have seen for this problem is that their email address is unconfirmed. You can either switch to adding them by their Login ID or SIS ID instead and then it will usually recognize the user. However, if the issue is unconfirmed email addresses, you may want to make sure you work on getting these confirmed too.