It seems strange. I'm testing the plugin against 9 different sites and I was unable to reproduce your scenario.
I think the problem is related with the latest changes, but no changes were made affecting Maxmind functionality.
Well, there is one. I added an extra control when Apache lacks the Multibyte String Extension. On that scenario, GeoIplocation can't run, since it depends on that extension, and the plugin will dump an error message.
The 1.7.50 fix should prevent users when this extension is missing. Even though, this wouldn't affect Maxmind functionality.
There is a explanation on this issue on the following topic Spy Option
Thanks for your comment on that matter. I'm currently checking other reasons for this behavior, and I let you know shortly.
Any other info you can provide would be very useful. Thank you.