You said you put the slider in the middle, but how much it's showing in the "Fee" field? It should be showing 0.0049
BTC since you have 0.0333
BTC and can only spend 0.0284
BTC (0.0333 - 0.0284). Go to Tools -> Edit -> check "Edit fees manually". Now you can for example, move all the slider to the left and lower your fee a little bit and press "Max" again.
E.g: Electrum is suggesting me a fee of 435 sat/byte if I put the slider in the left, but that's extremely overpriced. I sent a transaction with a 1 sat/byte yesterday and it took only 1 day to get confirmed (I saved up ~$5).
This won't spend anything until you click sign. Post a screenshot of this here?
Until you click Broadcast*