Thank you for taking the time to visit the Community to report this issue, although I apologize that you have not received a response.
First, please navigate to Help > About Quicken and provide the release that you are currently running.
May I ask that you please take a moment to review the steps and information available here and confirm the location of the data file? Is the file stored on the hard drive or the cloud drive?
Storing the file in a cloud drive may cause missing transactions as you have described. Please let me know!