To check your attestation status, use Play Integrity Checker on the Play Store. If you pass both BASIC and DEVICE integrity, try clearing data for Play Store.
Thank you!
Followed Munchy's vid instructions: tweaked few Magisk's Zygisk options, then patched safetynet_fix, cleared Google Play Services & Play Store's data. That solved the problem and worked beautifully now.
Thanks for your pointer and Munchy's video. Much respect & appreciated!