For the brave of heart, you may wish to actually look into the SCX/SCT table which is the basis of your coding. Each of the Objects ( buttons, textboxes, etc. ) have their own record and memo record. From your messages, I sense that the 'snippet' / method code which disappears is inconsistent -- or changes from run to run. What I am suggesting is that you open and browse a form, looking at the field names 'Properties' and 'Methods'. Since your complaint is the disappearance of 'Methods', I would look there.

select 0
use xxxxxx.SCX
locate for Objname = "desiredObject" && could be atc() or any other expr
edit NOEDIT
.
.
.
double click on the field 'Methods'

you should see the methods you have coded, I would look for odd shaped characters which may affect how VFP builds / stores the methods when compiling the APP's and EXE's. These odd shaped characters are within the 8 bit ASCII character set, but may have programmatic effects in VFP.

This is different from some of the other suggestions, and please note the NOEDIT on the edit command, which will keep your SCX/SCT safe from bad keystrokes -- not that you would make bad keystrokes, but it has happened.