My clients are not able to open my invoices and I sent one to myself and could only open it on my laptop but not my mobile phone - what has changed please?

Hi. Apparently not every phone or computer can open QB invoices even if its the most recent device "I've been told" 

I have had this issue for 2 years as you don't really know what a client has or hasn't opened even if it says SEEN as this does not mean the full invoice with all breakdown has been opened completely