I have a problem, when I save a drawing in PDF, the image (the company logo) in the title block does not appear in the PDF. I have a white box instead. I'm using Solidworks 2021, I tested the 2023 and I'm finding the same problem.
We had the problem many years ago (10-12 years or more...), and I don't remember the cause very well. Is the image in the background? What function or how did you insert your image? Possibly post your background plan to test it.
To save in pdf I prefer to go through a virtual printer, CutePDF Writer which will output the same thing as on paper, so if your logo is printed on paper you should find it on the pdf. For better quality when zooming in on the file, I check in the print settings, High quality
From one day to the next it's surprising, look in the export options by checking or not certain box if it changes anything: (save as > pdf then the Option button