It's a bit unfair for people when some issue is consider as BUG and people who bought it can't get update or any guide to make extension work like it mention. at least you should release guide to fix this issue for older version.
or keep selling BUG extension to people that support you.
I understand your point and agree with you. However, there are 2 things that we should consider:
1. The extension was released after you purchased the bundle, and it's quite new. We didn't intentionally want to sell buggy extensions.
2. There are sometimes bugs in the extensions and we're trying to fix as fast as possible. This bug was fixed just 1 day after it's reported and Florian (who reported it) was happy with the progress.
This fatal bug also relates to the new change of Meta Box plugin. We created a new mechanism (called storage) to handle saving data, which helps reducing a lot of code for term/settings/user meta extension. Unfortunately, the frontend extension didn't use that mechanism at first and we had to update it in version 1.0.3.
If you want to fix the extension work, just add this single line to the file class-mb-frontend-post.php.