Lost custom HTML themes after upgrading version

[spandan888]

what @himayun19 means to say is that he had added a custom theme based on @sharpdrivetek 's post

Anatomy of India's New GST Invoice Format

Thank you @lubos for the patience shown these past weeks and helping us out. I have modified my earlier custom template to suit the recent changes introduced in Manager. Users can feel free to use this custom template. You can find my earlier post and instructions below. What has changed? The value in words is default if Indian currency is set. So it has been modified accordingly. The “Shipped To:” field was not showing when it was left blank. So users had to type in the customer details a…

but then he upgraded to today’s version and lost the theme’s functionality

i havent upgraded, so cannot say whether this is an universal bug.