JumpRope has some practical limits to how much data can be displayed on the page at one time, particularly in the data-heavy gradesheet. While we are continually working to increase this limit and the related performance, you may see a warning that you have exceeded the limit (currently around ~15,000 scores) if you have an unusually large number of standards, assessments, or students in your class.
To resolve this issue, the first strategy is to organize your assessments into Units in the Plan page and to "collapse" the units in the gradesheet. A collapsed unit will save some screen space and will also defer loading the scores for the assessments in the unit until you expand it. By keeping only active units expanded, you can avoid hitting the per-page score limit and also increase the speed & usability of the application.
For more information about organizing your assessments into units, see this document.
To learn about collapsing and expanding columns in the gradesheet, see this document.
Thanks for understanding, and feel free to contact our support team if this does not resolve your issue or if you need further assistance.