declare -g reports as invalid option on MacOS (10.14.6) Bash (5.0.11)

[Ray Sutton]

Firstly apologies for not using bashbug, I'm having an issue on a
machine I'm rebuilding and don't have email readily available yet

The issue is on a late 2013 MBP running MacOS 10.14.6 and 
bash -version reports 5.0.11(1)-release (x86-64-apple-darwin18.6.0)

The error is occuring in my .bash_profile and reports as

-bash: declare: -g: invalid option
declare usage: declare [-afFirtx] [-p] [name[=value]...]

Which does not agree with the man page.

My work MBP (mid 2014) is running exactly the same version of both
MacOS and bash, the problem doesn't occur there

In both cases bash was installed via brew.

The behavior seems consistent with the original bash 3 declare
statement persisting after the bash 5 install which seems unlikely.

Any Advice on how to fix this issue?

Thanks

Ray Sutton