Thanks for clarifying this for us, marigavin1,
You didn't mention the size of the album you're not able to share. So, here are the album sharing limits:
Shared Albums limits
These are the Shared Albums hourly and daily limits:
• Maximum number of photos and videos from a single contributor across all shared albums, per hour: 1000
• Maximum number of photos and videos from a single contributor across all shared albums, per day: 10,000
These sharing limits are separate from the upload limits above. For example, in the same day you could upload 10,000 photos to My Photo Stream, then share those 10,000 photos or 10,000 other photos.
Some additional limits for shared albums:
• Maximum shared albums an owner can share: 200
• Maximum shared albums a user can subscribe to: 200
• Maximum subscribers per shared album: 100 (the number of subscribers on each shared album)
• Maximum combined number of photos and videos from all contributors in any one shared album: 5000
• Maximum number of comments per photo or video in a shared album: 200 (a comment can be either a like or a text entry)
• Maximum characters per comment: 1024
• Maximum number of invites a shared album owner may send per day: 200
My Photo Stream and Shared Albums limits - Apple Support
If you're still unable to share photo albums after verifying the size is accepted, we'd suggest that you contact Apple directly to investigate this further with you. You can find their contact details here: Contact - How to Contact Us - Apple
Kind regards.