I’ve checked your account and the thumbnails of your presentations load fine on my end. It means it is most probably caused by a firewall or other security software running on your computer. This problem could happen if you have recently upgraded your operating system or security software or if you are using a computer different from the one you normally use, like in an office or school environment.
To make sure that your firewall or security settings are not preventing your computer from accessing Prezi, please take the following steps:
Check that this is also the case with any firewall software, browser privacy add-on, or similar software that you may be running on your computer.
Please make sure that pop-ups are allowed in your browser privacy add-on or firewall software for:
Our website supports all major modern browsers, but for the best experience we recommend using the latest versions of Chrome, Safari, Firefox 64-bit or Edge.
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*Note: If you experience this issue from a protected network, you may need to ask the responsible IT person to make these adjustments for you. This is common if you are trying to access Prezi.com from an educational institution or a company network.