I guarantee the rubber is NOT the issue. You have dog eared your Wags (not a criticism, I did it also and now use Liquidators). If the dog ear is too close to the rubber on a solid channel the drag is inevitable until the new blade (burns in), that's why you're having no issues with the old rubber.
In a very early video of Waggas he addresses this very issue. The dog ear has to be pedantically set. Not too much nor too little. I see you're using Waggas 'split'. When looking down on the blade/dog ensure that the bend in is still free and not touching the rubber. Also the split bend down should still allow about 1-1.5 mm from bottom of channel to bottom of blade.
Remember that if you've changed your brand of rubber then the 'dog-ear' will probably need to be adjusted as all rubbers have fractional differences and are normally optimised for the manufacturers own channels
Finally GG4 added to eCover I've found lessens the slip not increases it. To add slip to eCover I add IPA (isopropyl alcohol).
To ensure that it's NOT the rubber. Use a standard Ettore Squeegee to test it. After all for the last century that's what they were designed to be used in...