Hello and thanks for your question.
Check and record the transmission fluid level after the engine has been off for at least 10 minutes. It should show overfull. Now start the engine and check the fluid again. It should drop down to the normal zone. If it does not drop or only drops slightly then the drive gear in the torque converter for the front pump is stripped out and the pump is not turning. The torque converter will need to be replaced and the pump driveshaft will need to be inspected.