In your photo the plant looks fine, you're not getting the yellowing to lower leaves to suggest mobile nutrients are lacking. You also aren't experiencing any leaf anomalies at the top of your plant to suggest a lockout. I think you're fine. Your EC is rising and pH lowering because the concentration rises as water is consumed and most everything else is left behind. This is pretty common while in late flower in DWC. You can lower nutrient concentration to save/extend your fertilizers but mainly keep up on replacing the water you're losing to keep your pH in range.

lockout may be causing it to not be able to uptake the required nutes

If the EC of the nutrient solution is lower than what the plant needs, then nutrients and water will flow from the plant through the roots into the medium, raising the EC; this is called the process of osmosis. For the stage of your plant, it should have an EC of 1.8 to 2. Change your bucket and prepare another nutrient solution with an EC of 1.8.

Does the EC go down or up? If its up you need 2lower EC.. Also u are changing solution every 7-10 days right. As with them drinking so much and taking in nutrients salt builds up in the roots U could just restart. Add just water. PH and after a few hours once the roots/plant have cleaned up some add nutes with fresh water. I haven't done many DWCs. But if the plants not eating. Lower ur EC until you get a drop.. Also if your RH is in the wrong window it could be causing the plants intakes issues. And been yours is 80% (just checked i reckon here's where ur issues are.