Updates to PDF not reflected on "Show on Card" Preview

[JWhiteFEI]

After updating a PDF on my SP site that is linked to a Planner Card, and marked "Show on Card", the changes to the documents are not reflected in the show on card preview. 

I am encountering this both on the iOS app, and desktop website. I have tried to remove and re-add the attachment, un-check and re-check show on card. I have waited approximately 12 hours since my last update, and the change is still not reflected in preview.

I was hoping that when I made changes to a pdf, I could save over the existing in SP Documents and the changes would reflect in Planner, instead of having to manually add a new attachment each time.

[#2]

@JWhiteFEI 

This seems to be a caching problem. I get updated previews as long as I use the browser's incognito mode or if I completely clear the cache. In Chrome you have to open the DevTools (F12) and then right-click on the regular refresh button next to the address bar and select the last option to clear the cache and do a full reload.

See also this idea and vote on it: https://planner.uservoice.com/forums/330525-microsoft-planner-feedback-forum/suggestions/31184449-up...