I tried to sync some photos by moving them to collections in my primary computer. They are some kind of synchronized in another computer because I can see the same number of photos in collection folder there but all the photos greyed out so I cannot do any editing there. BTW I am using the latest LR
I tried to sync some photos by moving them to collections in my primary computer.
This is not a "sync". It sounds like a manual operation.
There is no such thing as a sync between two computers using Lightroom Classic. (Is that what you are using? You don't say that). Lightroom Classic can only "sync" between one catalog on your computer and "the cloud".
Please describe the end result you would like, and we can help you get there.