Tough break on that mission, ram kills are so hard to set up, only to have arty ruin it. Definitely check the exact wording. If it says "survive the battle," then unfortunately dying at all will void it. If it doesn't mention survival, then contacting support is the move. Include the mission name and replay if you saved it.

Missions with super strict conditions can really test your patience. Sometimes it helps to take a break with something less punishing. When I need a change of pace from tank battles, I unwind with something like novapatti.io, quick card games where the results are much more in your control. Helps clear the frustration.