Please follow the instructions below and then try again.
Mobile app
If your device is running Android — clear the app cache (Settings → Applications → All apps → App name → Clear data → Clear cache) and then restart your device. If the difficulty is not fixed, please uninstall and reinstall the app from the mobile app store.
If your device is running iOS — try to change the network access point (switch to Wi-Fi network or vice versa to mobile internet). If the difficulty is not fixed, please uninstall and reinstall the app from the mobile app store.
Try out the action in the web version.
Mobile browser
Try changing the network access point (switch to Wi-Fi network or vice versa to mobile internet).
Reboot the device.
Perform a browser history and cache cleanup.
Use the private mode in your browser.
Desktop
Clear the cache/cookies in your Internet browser settings and refresh the platform page. See this page for instructions on how to clear it.
Temporarily disable antivirus / firewall or any other security software. After that, refresh the platform page.
Try using an alternative browser (for example, Mozilla Firefox).
Use the private mode in your browser.
Device settings
Check the SMS receiving settings on your device.
Check whether there is a ban on receiving SMS from certain message recipients (you can check the correct settings and information about restrictions with your service provider).
Make sure that there is enough storage for text messages.
Turn the phone off - remove the SIM card - insert it again - turn the phone on and try again.