すべてのシートは青です

The most likely cause would be storage of the sheets outside of its specified environmental spec’s.  Did you buy the sheets from HP or an authorized dealer?  I would suggest contacting your supplier for a replacement.

Bob Headrick,  HP ExpertI am not an employee of HP, I am a volunteer posting here on my own time.If your problem is solved please click the “Accept as Solution” button If my answer was helpful please click the “Thumbs Up” to say “Thank You”