No credits since march despite several purchases in March and April

So you're looking for VIP rebates then. Rebates are calculated after the end of the month and given by the 15th of the next month. So it's too early to see credits pending for April purchases then. Support will double check March, but keep in mind that if
you had opted into the "Simply Rewarding" offer, any purchases that went towards that offer would not have counted towards your rebate.

In order to receive credits for purchases, they either have to be eligible for a specific offer on the site at the time, or you need at least 1 star level in order to receive VIP rebates.

I know. I'm a 5 star vip

In order to receive credits for purchases, they either have to be eligible for a specific offer on the site at the time, or you need at least 1 star level in order to receive VIP rebates.

Are there any specific offers you're looking for credits from?

Hello FallenRAVEN47,

We see multiple Credit and deposit events on your account, which you can review via the MyStatement on the MyRewards page. You can also confirm these deposits as currency on the commerce page. You may have missed them since they are categorized as refunds
with a negative amount. For example, your recent deposit on April 12th was spent on your Just Cause add-on purchase on the 13th.

In addition, from our FAQ:

When will my MyVIP Rewards Credits be deposited into my Microsoft account?

The total Rewards earned will be calculated at the end of each month. Typically you'll receive your MyVIP earnings in your account by the 15th of the following month, though this is subject to the program's current deposit
terms. Be sure to keep an eye on MyStatement on the
MyRewards page to track your progress and watch your Rewards Credits total grow!

We have not yet calculated last month's MyVIP, so it is too early to see the Credits pending. In addition, most of your purchases in March were consumables, which are not eligible for MyVIP, also as stated in the FAQ:

What content on the Xbox Store is eligible for MyVIP?

Normally, most purchases for Xbox 360 and Xbox One from the Xbox Store qualify, including full Games on Demand titles (excluding game pre-orders), arcade games, indie games, game add-ons, game Season Passes, movies, TV shows, TV seasons, themes and avatar
items. In-game consumables, Xbox Live Gold memberships, Groove Music Passes, Microsoft Movies & TV Season Passes, and the purchase or redemption of Microsoft Points or Xbox Gift Cards, still do not qualify.

While your free to play consumable purchases went towards some FREEdom Rewards offers, they did not complete any of them.