Attachment disabled when replying user request

Attachment disabled when replying user request

I have implemented the Service Desk system to my company for around 3 weeks. When replying a request, it was able for me to attach a file. However, I found the button of attaching files disappeared these two days. I wonder if the max limit of storage has been exceeded. Does anyone know what is going on for this situation? What is the storage limit? And how I can remove the old attachments in the system. Many thanks!

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