Hi @Bob_S 

i am afraid it is correct, internet explorer is indeed required and yes it is end of life in terms of support. 
 

Nintex provides its own forms technology which is web based on is supported on all modern browsers as a replacement of infopath. 
 

At the moment your only option is to request assistance from your IT department to ask for them to provide you with an IE install. 
 

alternatively you can navigate directly to the task list where this form is located, gather the URL and open it directly from the infopath application if it will allow you, I am not sure however what the behaviour might be or if it will work at all. 
 

Please also be aware infopath is also end of life. 
 

Problem was solved by using the ‘Reload tab in Internet Explorer-Mode’