When using API to get the activity, the fixPlanning key is duplicated, thus the json cannot be exploited in Excel Power Query.
Exemple of returned json for /api/index.php?uri=activity/1 :{"identifier":"id", "items":[{"id":"1", "reference":"-DEV-1", "name":"Rédaction spécification", "idActivityType":"19", "nameActivityType":"Development", "idProject":"1", "nameProject":"Projet Rémy 1", "externalReference":"", "creationDate":"2022-08-09", "lastUpdateDateTime":"2022-08-09 18:18:49", "idUser":"3", "nameUser":"Rémy", "idContact":"", "nameContact":"", "originType":"", "originId":"", "refName":"Rédaction spécification", "description":"", "idActivity":"", "nameActivity":"", "idStatus":"1", "nameStatus":"recorded", "idResource":"", "nameResource":"", "idMilestone":"", "nameMilestone":"", "fixPlanning":"0", "paused":"0", "handled":"0", "handledDate":"", "done":"0", "doneDate":"", "idle":"0", "idleDate":"", "cancelled":"0", "result":"", "validatedStartDate":"", "plannedStartDate":"2022-08-09", "realStartDate":"", "initialStartDate":"", "validatedEndDate":"", "plannedEndDate":"2022-08-22", "realEndDate":"", "initialEndDate":"", "validatedDuration":"", "plannedDuration":"10", "realDuration":"", "initialDuration":"", "validatedWork":"10.00000", "assignedWork":"10.00000", "realWork":"0.00000", "leftWork":"10.00000", "plannedWork":"10.00000", "validatedCost":"", "assignedCost":"", "realCost":"", "leftCost":"", "plannedCost":"", "progress":"0", "expectedProgress":"0", "wbs":"1.2", "priority":"500", "idActivityPlanningMode":"1", "nameActivityPlanningMode":"as soon as possible", "color":"", "minimumThreshold":"0.0000", "indivisibility":"0", "fixPlanning":"0", "paused":"0", "workElementCount":"0", "workElementEstimatedWork":"", "workElementRealWork":"", "workElementLeftWork":"", "workOnRealTime":"0", "idProduct":"", "nameProduct":"", "idComponent":"", "nameComponent":"", "idTargetProductVersion":"", "nameTargetProductVersion":"", "idTargetComponentVersion":"", "nameTargetComponentVersion":"", "targetValue":"0", "actualValue":"0", "pctRate":"0", "refName":"Rédaction spécification"}] }