I saw the wrong one used recently.

Problem:
“In line” and “inline” are not synonyms.

Explanation:
“In line” tells where and is an adverb: “Bob is in line to receive a raise.”
“Inline” tells what and is an adjective: “Bob enjoys inline skating.”

Solution:
Use “in line” when you want to indicate where something or someone is.
Use “inline” when you want to describe what something or someone is.