I'm stuck with the same problem. It's happened 3 times in the last 3 weeks. The problem stems from the differences between a Chat session and a Tasks session. I call the two AI versions 'Chat-Copilot' and 'Tasks-Copilot'. They know each other and can format data for each other. This is a summary I asked Chat-Copilot to provide, to guide their usage:

⭐ Summary: How Chat‑Copilot and Tasks‑Copilot Differ, and How to Avoid TC Limits

I’ve been using both Chat‑Copilot (CC) and Tasks‑Copilot (TC) extensively, and I wanted to share a brief summary that may help others understand how each tool works, why TC sometimes stops responding, and how to avoid running into limits.

⭐ 1. Chat‑Copilot and Tasks‑Copilot serve different purposes

Chat‑Copilot

• Real‑time conversational AI
• Great for brainstorming, drafting, coding, calculations, and iterative design
• Stateless — each message is processed independently
• Very stable and rarely gets stuck

Tasks‑Copilot

• Designed for multi‑step workflows
• Can create and maintain documents
• Runs long‑lived background tasks
• Maintains persistent state
• More powerful for structured work
• More fragile because it depends on a task‑execution pipeline

These two systems are independent. Chat can work perfectly even when TC is frozen.

⭐ 2. Why Tasks‑Copilot hits limits or becomes unresponsive

TC can stop responding when:

• A task runs too long
• A multi‑step workflow fails mid‑execution
• The task state becomes corrupted
• The weekly quota system triggers
• The backend fails to reset on Friday
• Too many “pipeline‑style” requests are issued in a short time

When this happens, TC may:

• stop responding entirely
• ignore all prompts
• remain stuck across all devices and browsers

This is a backend state issue, not a browser or device problem.

⭐ 3. How to avoid triggering TC limits

Here are practical ways to keep TC healthy:

Use Chat‑Copilot for:

• brainstorming
• engineering design
• calculations
• drafting text
• generating diagrams or prompts
• step‑by‑step reasoning

Chat handles these extremely well and never “uses up” TC capacity.

Use Tasks‑Copilot only for:

• creating structured documents
• maintaining long‑form reports
• assembling multi‑section deliverables
• tasks that explicitly require persistent state

Avoid these patterns in TC:

• “Build the entire document end‑to‑end”
• “Run this whole workflow”
• “Generate all sections at once”
• Rapid‑fire edits or repeated task triggers
• Very large or complex requests

Instead, break work into small, single‑action steps.

⭐ 4. When TC gets stuck, what can users do?

For consumer Microsoft 365 Personal accounts:

• There is no user‑accessible reset button
• Frontline support cannot reset TC’s task state
• Creating a business account does not fix the issue
• The only options today are:
  • submit feedback
  • post on the Tech Community
  • wait for the backend to refresh

This is a known limitation of the current TC preview.

⭐ 5. What would help users going forward

A few improvements would make TC much more reliable:

• A user‑visible “Reset Task State” button
• Error messages instead of silent failures
• More predictable weekly resets
• Support tools that allow agents to clear stuck task containers

I am having the same issue, I actually created another account to circumvent this issue, and that is also hitting the same wall. 
I’ve force ended all tasks, deleted all tasks, submitted feedback, TRIED to contact MS Support-done all the things that Copilot has recommended to resolve.

This is crap.  

Good luck. I’ve had this issue for over 7 days now, and it did not reset on Friday. I keep getting the runaround from Customer Service, and I spent over 2 hours online with them tonight. I was made to feel like I was doing something wrong. I’m completely appalled by how I was treated, and they kept referring to the free tier even though I am not on the free tier.

I am getting the same error and have been trying to get this resolved since last Friday, No luck at all getting help. I keep getting talked to like it's my fault and not the agents. I am staring to get the feeling it this is not resolved in a day or so I will cancel my subscription.