Having a master project open locks all subprojects, even though we did not 'link to project'

[Becky2495]

Hi, I am having two issues with Microsoft project (2016)...

For context: We are using MSP to track a large project so we have multiple subprojects worked on by different teams, which are saved to SharePoint to allow everyone to access them. Once a week we create a 'snapshot' of the data by putting the sub-projects into a master plan. When I insert the sub-projects into the master, I uncheck the box 'link to project' as we had issues where this would cause all of the sub-projects to open 'read only' when the master plan is open.

1 - When I have the master plan open, there don't seem to be any issues with the sub-projects, but for one or two members of the team, when they have the master project open, it makes all of the sub-projects 'read-only' as well as the actual master that they have just opened. I'm very confused why this would happen if the sub-projects are not 'linked' to this master in any way, and also why the file itself that they have opened suddenly becomes read-only for them?

2 - Often people will try to open a sub-project and it will be 'read only' even though no-one else has the file open. Also, we keep finding that when people make updates to their sub-project, these are lost even after they have saved - and sometimes updates they have made do not appears for others, but when they open the file again they can see their updates (almost as though there are different versions of the file opening for different people).

Any help is much appreciated!

[#2]

Can I suggest a slightly different approach? When creating your snap shot I would copy all the plans from SharePoint into a local drive or maybe something on One Drive. As you're only interested in looking at the combined master it doesn't matter that you've taken copies. In this way nothing that you do can possibly impact anyone else and they can continue to use their sub plans as normal.
When I am acting as a human MS Project Server/on line I will have three folders: Input, Programme plan and Output. I receive the version controlled plans from the PMs into the input folder, open then and save as into the Programme Plan folder over writing the standing copy in there which doesn't have any version control. The master programme plan is a master plan with the plans inserted and linked. I do what ever I need to do on the Programme plan including making changes as needed to the sub plan, running reports etc. When I am done I save each sub plan out into the "output" folder with a version control and return it to the PM.
In this way I can also have a resource pool running in the Programme Plan (though I have to remember to remove the association of the output files to the resource pool file and also be careful that the input files don't contain "new" resources which are actually duplicates of existing one).  I did a bit of a blog post explaining this method: https://www.summarypro.co.uk/blog/working-with-a-resource-pool-and-distributed-project-files.aspx
This 3 folder method is useful but would probably be overkill for what you need as you're only interested in a snap shot and aren't interested in editing the sub plans etc.