If you have "Different First Page" selected in the section before the landscape section that will apply in the new landscape section as well. Page numbers are fields that are generally in headers and footers and follow rules for headers and footers.

Try attaching a sample document with the problem but without proprietary or confidential information. How to attach a screenshot or file in this forum.

In the meantime, here are some resources that may help:

• Page Numbers in Word 2007-2019 (365)
• Header/Footer Settings Recap