Identifying the cause of my first scorch

Biab
4500 ulwd element
6 brews with no scorch of boiled wort...no issues with melting the bag

Pretty upset to lose the biggest dipa I've attempted...most expensive.

Possible causes:
*wanted to boil off more during 90 min boil. First time pushing a more vigorous boil. I usually keep it pretty gentle rolling.

*no hop bag and used a much larger amount of pellet hops this time. Huge fail just in terms of filtering the wort for fermentation. Last batch I clipped a large mesh bag to the side for whole cones and had no scorch.

*first time using corn sugar in the wort boil.

Perhaps the trouble is a combo of all three?

It seems like most people report scorched flavor coming from burnt sugars, so in your case I'd be curious about the corn sugar. Did you just dump it in, or stir it in slowly?

I use a 5500 Watt HD element in my BK, and haven't scorched wort...yet. Not saying you did this, but I read a comment on this site awhile back, it makes sense, so I follow it.

Don't set your BK element to max when heating first runnings, especially with high OG beers like IPAs. First runnings have such an uber high sugar concentration that any heat applied by a high wattage element could lead to scorching. I wait until all wort is transferred into BK before turning up the heat. The 2nd and 3rd runnings will dilute the 1st runnings.

A film can build up on your element after several uses and cause scorching. Scrub with a scotchbrite pad after each use.

Im pretty sure my issue was with the corn sugar. I had assumed the boil was vigorous enough to keep it in suspension. Again, I've never made a better this big. Live and learn. 10 oz of lovely hops and most of a day wasted. I had also worked hard to rinse the year from a previous beer. Reused the slurry. Ugggg.