Check the earning history screen to verify that the redemption has been completed (gems have been subtracted).
If extra bars are not reflected in your account
Extra bars are added to the right side of the distance bars you originally had, and are displayed by tapping the area where the bar is displayed and sliding it sideways.
Please note that sliding operations may not be possible on some devices, such as some of those manufactured by LG, due to device-specific issues.
Even if sliding doesn't work, the bars for which you have redeemed gems still exist. Please check how many bars you have filled by looking at the "You can earn XXX times more" indicator below the "Can earn 1 more times" button.
If other items are not reflected in your account
Exit the app from the App Switcher (Task List) and then restart the app.