Could someone check these sentences and make them sound more natural?. Please feel free to edit or make any changes you deem necessary
Due to stockouts of materials and supplies in our store of Madrid , we have been running low on stock on some materials. I submitted a claim but I haven't received any answer yet
When I made a transfer into the system , these kinds of materials go missing and I do not know when I have to restock them
Could I activate on my own ? Or Should I contact someone?
Although everything seems correct , the system does not run properly
Due to Robert being on sick leave , The workload is increasing more and more.