I'm happy to see you posting here in QuickBooks Community.
Can you please provide additional information on how you separate your financial statement in QuickBooks? And, what report did you pull up to view the specific date of your data? I'd appreciate any further details so I can present accurate information.
If you separate the FS by splitting the transactions in your QBO account, I'd suggest making sure that you run the report with the correct date of the transactions. To verify this, you'll need to go to the Register page to review the date of the entries. This way, you'll be able to run the report with the correct date of data.
Select the Accounting menu and choose the Chart of Accounts section.
Find and select the account history you want to review.
From the Actions column, select Account history.
Choose the Filter icon. Then select the filters you want you to apply. You can use the Find field to search by amount, reference number, or memo.
Hit Apply. Then, check the date in the Date column and you can click the Edit button to see more details.
Once done, you can now try running the report again to verify if you'll be able to see the particular data.
If the issue persists, data in your browser might be the reason that you're unable to date the specific data you want to view in your report from Jan -19 to Mar -19 with Jan-18-mar19. With this, I'd suggest accessing your account via a private or incognito window to check if this is a browser-related issue. At times, data stored for a long period causes unusual behavior to the browser.
You can use either of these keyboard shortcuts:
For Google Chrome browser: Ctrl + Shift + N
For Mozilla Firefox browser: Ctrl + Shift + P
For Safari browser: Command + Option + P
If it works, then your main browser may have too much historical data from previously visited websites that cause this kind of behavior. Just go back to your regular browser and clear the cache to delete those temporarily stored files and browsing history. You can also use other supported, up-to-date browsers as an alternative.