If you're unfortunate enough to have the release of Cadnetix software where the via anti-pads disappear when you move the vias, I have a workable band-aid for you.
Cadnetix's solution is to tell you that you should upgrade to the latest version software... unfortunately for some of us, this is no longer possible.
The version of software where this bug occurs is F1.1A, or thereabouts. The bug had a short life span, since, as soon as it was discovered, a patch tape was sent out to those customers on maintenance, which exterminated the bug.
To determine if your version of software has this bug, make a copy of a job that has plane layers.
View into the job. Turn on one of the TRACE layers and one of the PLANE layers.
Pick a spot somewhere outside of your current job work area to perform this experiment.
Draw a trace, press the 'SPACE' bar to drop a via, then continue to draw more trace at a 90 degree angle. After you dropped the via, you should be able to see both the via, and its' anti-pad (on the plane layer). If not, pan the screen a bit to refresh the graphics.
Now, pick one of the traces and move it a bit (or just selecting it, getting ready to move it and then releasing it, will have the same result.)
If you have done it properly(?), and you have the bug in your software, the anti-pad will have disappeared from the PLANE layer.
Guess what this does? When you go to photoplot the layers, there will be no ANTI-PADS on the PLANE layer (where you have moved the vias) which means that you have a via connecting both planes together... along with the trace that is connected to this via. Boooo!! Not Good!
To correct this problem... leave this trace & its' via, and SAVE & CLOSE. Run a 'Recovery Compile' on this job. After the compile has completed, take a look at the exception document. You should see a message indicating that the anti-pad was 'fixed'. View into the job and visually verify this.
One drawback. If the via is connected to a plane... and gets fixed, it will only get an anti-pad... not the original thermal pad, when it gets fixed. You will need to go back in and reconnect any PLANE connections. Small price to pay for a good board.
(Ok, ok... Cadnetix tells us to run 'recovery compile' after every job anyway... but some of us... myself included, do not always do so.)