Let's open your QuickBooks Online (QBO) account via a private or incognito window and print your reconciliation report for there. This way, we can check if this issue is caused by cache from the browser.
Cache stored for a while causes unusual behavior to the browser that affects the [performance of your QBO account. You may use these keyboard shortcuts in opening a private/incognito window:
Google Chrome: Ctrl + Shift + N
Internet Explorer & Mozilla Firefox: Ctrl + Shift + P
Safari: Command + Option + P
If you're able to print the report via a private or incognito window, then we'll need to clear your regular browser cache. This will erase the cache stored from the browser and prevents unusual behavior.
However, if the issue persists, I suggest using another browser. This way, we can check if this is a browser-related issue.