As someone actively trying to hire front-end developers I've come to see Hack Reactor as a red flag. Unless the candidate was selected as a tutor for the next batch I rarely let them past the resume screen.
In general, most companies look at any bootcamp as a red flag. However, I have seen much better results from students from Hack Reactor over others like General Assembly.
Was this due to poor experience with people from the program in the past?
At the phone screen level, yes. Took about 10 calls for a disappointing pattern to immerge.