Contextual Snippets in UltiSnips not working

Question

I have been using vimtex with UltiSnips for a while on Linux platform and it has been working just fine.

Recently, I switched to MacBook Air M1 for the same and installed the above mentioned plugins to work with MacVim using vim-plug. All UltiSnips snippets are working (expanding) except for those which use a context by which I mean that regular snippets expand as expected whereas the snippets involving a context do not expand. Also, I found out that if I comment out the context "math()" from snippets then they do expand. So basically the problem now is that the context environment is causing problems with snippet expansion. A sample for my snippets is provided below.

I suspect this is due to MacVim running on top of Rosetta 2 but cannot be sure as nothing else has changed (maybe someone using same setup as me but on regular Intel chips can pitch in for more data).

Can someone help me figure out this thing?

Snippets :-

1. Regular snippets which do work :-

snippet pack "creates a usepackage command" bAm
\usepackage{${1:package_name}}
endsnippet

2. Context snippets which do not work (here the context is math()) :-

global !p
texMathZones = ['texMathZone' + x for x in ['A', 'AS', 'B', 'BS', 'C', 'CS',
'D', 'DS', 'E', 'ES', 'F', 'FS', 'G', 'GS', 'H', 'HS', 'I', 'IS', 'J', 'JS',
'K', 'KS', 'L', 'LS', 'DS', 'V', 'W', 'X', 'Y', 'Z', 'AmsA', 'AmsB', 'AmsC',
'AmsD', 'AmsE', 'AmsF', 'AmsG', 'AmsAS', 'AmsBS', 'AmsCS', 'AmsDS', 'AmsES',
'AmsFS', 'AmsGS' ]]

texIgnoreMathZones = ['texMathText']

texMathZoneIds = vim.eval('map('+str(texMathZones)+", 'hlID(v:val)')")
texIgnoreMathZoneIds = vim.eval('map('+str(texIgnoreMathZones)+", 'hlID(v:val)')")

ignore = texIgnoreMathZoneIds[0]

def math():
    synstackids = vim.eval("synstack(line('.'), col('.') - (col('.')>=2 ? 1 : 0))")
    try:
        first = next(i for i in reversed(synstackids) if i in texIgnoreMathZoneIds or i in texMathZoneIds)
        return first != ignore
    except StopIteration:
        return False

keywords1 = { 'a' : '\\alpha',   'b' : '\\beta',   'g' : '\\gamma', 'd' : '\\delta', 'e' : '\\epsilon', 'z' : '\\zeta',   't' : '\\theta', 'i' : '\\iota', 'k' : '\\kappa',   'l' : '\\lambda', 's' : '\\sigma', 'o' : '\\omega',  'p' : '\\psi',  'A' : '\\Alpha',   'B' : '\\Beta',   'G' : '\\Gamma', 'D' : '\\Delta', 'E' : '\\Epsilon', 'Z' : '\\Zeta',   'T' : '\\Theta', 'I' : '\\Iota', 'K' : '\\Kappa', 'L' : '\\Lambda', 'S' : '\\Sigma', 'O' : '\\Omega', 'P' : '\\Psi' }

keywords2 = { 't' : '\\tau', 'p' : '\\pi', 'f' : '\\phi' , 'm' : '\\mu', 'n' : '\\nu', 'e' : '\\eta', 'T' : '\\Tau', 'P' : '\\Pi', 'F' : '\\Phi', 'M' : '\\Mu', 'N' : '\\Nu', 'E' : '\\Eta'}
endglobal

######################################################################

context "math()"
snippet ";([a,b,g,d,e,z,t,i,k,l,s,o,p,A,B,G,D,E,Z,T,I,K,L,S,O,P])" "Greek Letters 1" rAm
`!p snip.rv = keywords1[match.group(1)]`
endsnippet

######################################################################

context "math()"
snippet "'([t,p,f,m,n,e,T,P,F,M,N,E])" "Greek Letters 2" rAm
`!p snip.rv = keywords2[match.group(1)]`
endsnippet

######################################################################

Answer 1

The problem is that you have updated your plugins in the transition Linux to Mac. This also brings a major update of Vimtex, in which the syntax plugin has been included as part of Vimtex. Part of the syntax script changes are to simplify the math zones.

The exact issue you raise is discussed here, and this comment should provide the required change, repeated here for convenience. Change the top lines of your context script to this:

global !p
texMathZones = ['texMathZone' + x for x in ['', 'X', 'XX', 'Env', 'EnvStarred', 'Ensured']]

Edit: One can simplify the global part by using a built in function from vimtex:

global !p
def math():
    return vim.eval('vimtex#syntax#in_mathzone()') == '1'
endglobal