I wouldn’t expect any high speeds going up grades with watts below 100.
Can I ask what your weight, height, and age is.
Are you shifting gears while riding and not just increasing your cadence?
I would figure with a HR of 116 with watts of 94 you should have an FTP around 200 watts. What do you have your FTP set at?
Speed within Zwift is not calculated but cadence, this will help you in how it is calculated: How Does Zwift Determine My Speed?