#1

If I type a #tag on an indented line following a # header the tag does not become a link. In other words, if the tag is in the section under a header that will be slightly highlighted in preview mode.
Example:

test header

- #tag is not clickable
- neither is #this one
  • but #this one is fine
#2

Indented text, like the following:

#test

is considered a code block in Markdown.

In other words, you are trying to create an indented list but are indenting the list too early.

The following text renders problematically, as you’ve described:

# Test header
	- #Test

…becomes:

Test header

- #Test

But this:

# Test header
 - #Test

…renders correctly:

Test header

  • #Test

Note that the behaviour is the same here in Discourse. Markdown is a funny thing sometimes, sadly!