Unable to edit some records in SQL
The "Write Conflict" dialog is discussed in the Microsoft documentation for MS Access here:

Write Conflict dialog box


  Microsoft Access displays the Write Conflict dialog box when you and another person are attempting to write to the same record in the database at the same time.


That seems pretty straightforward - if other people have access to the SQL Server table (likely), then they have possibly changed the row you're trying to change since the last time results were loaded for you.  One way to work around this problem is to periodically refresh your view of the table (for example, after each edit you make).

In practice, there are some caveats to this process with SQL Server specifically around NULL values in the data rows, as well as the presence of a Primary Key and / or Timestamp definition for the rows.  These are discussed in this Stack Overflow post: 

Editing Record issues in Access / SQL (Write Conflict)