VBA Security and WorkSheet Copy Puzzle

An Excel VBA Addin is running the following code in a regular module, modifying another workbook which contains a sheet called "Master List".

Whether the code makes it to MsgBox "1" or not depends whether macros are enabled in the workbook (not the Addin (!)) If Macros are not enabled, it prints a "0" and then stops (with no error conditions) I know it's made a copy because I see "Master List (2)" as a sheet. But it does not print "1" (!) If Macros are enabled (either with a user permission, or perhaps the workbook is in a trusted folder) the code proceeds through MsgBox "1" and beyond. The sheet Master List does contain events code, if that helps. On the other hand I've turned events off. I've double checked the right workbook is referenced via Application.WorkBooks(1) (so that it's not referring to the AddIn, but rather the "ActiveWorkBook") What's going on???

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Thanks for the reply. Let me expand a bit on situation:

(1) The Addin scans workbooks loaded into Excel (via a App_WorkbookOpen(ByVal Wb As Workbook) event in the Addin's ThisWorkBook object). If it finds that a certain sheets exists, it will then proceed to modify that workbook. Such a workbook contains vba code itself.
(2) It may be that the loaded workbook is being loaded for the first time, and Excel's default is to turn macros off and notify the user.
(3) So in that event, macros run in the Addin, but Excel notifies me that "Macros have been disabled" which I take to refer to the loaded workbook, since my macros in the Addin continue to run, through a bunch more Addin code (many lines) however:
(4) If I don't give permission to enable macros (by responding to the "Macros have been disabled" notifiation bar) the code hangs at the indicated place (just stops). It stops specifically just after the worksheet.copy code.

So it seems that vba code is running in the Addin code, although (so Excel says) disabled in the loaded workbook. Does this make any sense?