I had met this problem a few times when I open pdf in illustrator.
The pdf layer will become a clip group and the text will become like this (problem.jpeg).
The font size change to big and small for every other character (eg. 12pt and 7pt).
But when I copy the text and paste it without formatting, it becomes normal.
And all the paragraphs are broken down one by one row instead of one paragraph.
What's happened and how can I solve this problem?
Hi if you are making this pdf try to make a group yourself when you are safe as pdf and check...regards
Looks like a PDF that was not made with Illustrator.
Illustrator can only reliably open a PDF that was created in illustrator and saved with Illustrator Editing Capabilities checked.
Sorry to hear about this experience. I agree with Ton and Lambiloon, it seems that this PDF was not made with Illustrator editing capabilities. If that is the case there can be issues opening such files in Illustrator.
However, if this PDF was created in Illustrator but is still acting up, I would request you to share a few more details like:
Looking forward to hearing from you.