We are having an issue for one of our users editing in a geometric network. Several geometric network editing toolbar buttons are not available for use. This error does not occur when I open the same MXD. Both the user and I are on ArcGIS Desktop 10.6.1 Advanced License on Windows 10.
When I open the MXD, all tools are available:

When the user opens the MXD, all buttons besides connect and disconnect are greyed out:

We have verified that the only 1 feature (the one intended to be edited) was selected on both computers.