I am unsure what part you are saying isn't working, I see some code, and I see some pasted code, but what is exactly wrong.
Either way you cannot set the DisplayMode of Button one, with the code you have in Button 2, not exactly
Either
1. You have to set some variable in button 2 that changes button 1s display mode
2. Add the code to button 1 instead of 2
3. In Button 1, set its DisplayMode whatever Button 2s DisplayMode is
But the code you have above, looks like what you put in button 2 as your description is confusing.
Please clarify if that code is in button 1 or 2 and if its in 2, what are you doing in 1 that would make it work?
Like you said said this is in Button 2
If 'Invoice Type' "Install", and "Other" title NOT in the Collection, and the Gallery count equals 10, AND all the titles (except "Other") appear in the DisplayName
of Install_Job_Image_Collection then set Button1 (Save Job) DisplayMode to Edit else Disabled.
But that code won't work as the syntax is wrong.
You said
I want to control the DisplayMode of Button1 with the following formula.
but then immediately talked about button2 and showed no code for button 1
Button2 (AddMediaButton) 'OnSelect' has the following.