I cannot see the tasks assigned to me

I still cannot see it in my Profile > Tasks > Assigned to me  > Incomplete

I created a Task Report, specifically for the tasks on that page, but they also don´t appear.

I have rights in the page to edit. 

Thanks Karen. Good detail. If it's missing from the Task Report for that page too and you've got edit rights, then permissions and the @mention aren't the blocker here, which points at the task not being indexed.

First thing I'd try is to open the source page in edit and publish it again without changing anything, since a re-publish forces a task resync and usually gets the task registered. Do the same on the page holding the report. If it still doesn't show after that, it's the content index, and an admin can go to General Configuration > Content Indexing and hit Rebuild on Site reindex, which also rebuilds the task report index. I've seen that clear up tasks that were created but never got indexed.

One more thing while you're in there, does the task have actual text next to the checkbox, with your name as the first @mention on that line? Empty tasks, and ones where you're not the first person mentioned, won't turn up anywhere. If you paste how the task line looks I can narrow it down.