Hello @MalachiRiley
Thank you for contacting the Instructure Community. You were then able to upload the assignment successfully? Or an older file you had saved? Were you using the reply/submit box to insert - document - upload document or had you first uploaded it to your Account - files? Sometimes, those account files get full as it stores all the images, videos, etc. that you upload to your courses. Check it and scroll to the bottom - it will tell you if you have reached your capacity for file storage i.e. 452Mb/500mb and this can stop students from uploading files especially larger ones like Powerpoint. Delete old files you don't need here from past courses by clicking the three dots on the right and delete.
If that isn't the issue and you have plenty of space, It was likely your internet browser and we recommend clearing the cache and cookies or trying another browser.
In Chrome
On your computer, open Chrome.
At the top right, click the three dots
Click settings
On the left, choose Privacy and Security
Then, clear browsing data
At the top, choose a time range. To delete everything, select All time. I suggest at least 4 weeks
Next to "Cookies and other site data" and "Cached images and files," check the boxes.
Click Clear data.
If that still doesn't work, try another device or browser or you can also contact Canvas support who can look at the specifics of your account, course, and file.
How do I contact Canvas Support? - Instructure Community