Hi,
Thanks for the clarification on the issue.
I was able to reproduce your issue and with some configuration I have also reproduce it in my local website.
In order to fix the issue, the best is to add some "checks" in the view "checkout | address_select" and replace
for(var k in el_sel.options) {
By
for(var k in el_sel.options) {
if(!el_sel.options.hasOwnProperty(k))
continue;
And same thing for
for(var k in ot_sel.options) {
With
for(var k in ot_sel.options) {
if(!ot_sel.options.hasOwnProperty(k))
continue;
In the view you will have make the replacement several times (and be careful on the "ot_sel" and "el_sel").
Internet Explorer does not deal like other browsers for the "for()" while looking at the content in a dropdown ; the extra check will avoid that issue.
Regards,