Hi,
The invoice was displayed without the correct HTML headers ; so the "component.css" from your template and the HikaMarket CSS wasn't loaded.
We fixed that in HikaMarket 1.5 but I can assure you that your view override was not removed.
I think the changes you see are related to the inclusion of the CSS files.
You can use the "styles CSS" in HikaMarket in order to put some CSS rules to re-get the display you got.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.