Hi palacios.madrid,
We appreciate you reaching out to us. We understand that you are experiencing issues with markups that are created on your iPad.
We’d like to gather additional details that may help us be in a better position to assist you.
Do the markups show correctly when viewed on the iPad?
If yes, let’s check if the issue persists when signed in on a different user account on your Mac.
This step may help further isolate the issue
The article below can help if you do not have any other user account to test with.
Set up users, guests, and groups on Mac
Also, let’s check for a software update and make sure that you are running the latest version of iPadOS.
While it isn't inherently assured that an update will resolve the issue, updating to the latest software version for your device can help isolate potential software issues.
Kindly secure a backup and update.
How to back up your iPhone, iPad, and iPod touch
Update your iPhone, iPad, or iPod touch
If possible, try to view your documents with markups on a different macOS device.
This step can help further isolate the issue.
Take care!