[Shop] More than 5 shops breaks the !shop buy command menu

[njhargis]

I have added 5 shops and !shop buy works great, upon adding the sixth shop my buy command begins to break.
Log below.

Exception in command 'shop buy'
Traceback (most recent call last):
File "/home/neil/redenv/lib/python3.9/site-packages/discord/ext/commands/core.py", line 85, in wrapped
ret = await coro(*args, **kwargs)
File "/home/neil/.local/share/Red-DiscordBot/data/Steamboat_Bill/cogs/CogManager/cogs/shop/shop.py", line 185, in buy
shop, item = await menu.display()
File "/home/neil/.local/share/Red-DiscordBot/data/Steamboat_Bill/cogs/CogManager/cogs/shop/menu.py", line 19, in display
msg, groups, page, maximum = await self.setup(data)
File "/home/neil/.local/share/Red-DiscordBot/data/Steamboat_Bill/cogs/CogManager/cogs/shop/menu.py", line 42, in setup
groups = self.group_data(data)
File "/home/neil/.local/share/Red-DiscordBot/data/Steamboat_Bill/cogs/CogManager/cogs/shop/menu.py", line 162, in group_data
grouped.append(self.sorter(data[idx : idx + 5]))
File "/home/neil/.local/share/Red-DiscordBot/data/Steamboat_Bill/cogs/CogManager/cogs/shop/menu.py", line 154, in sorter
return sorted(groups, key=lambda x: x[1]["Cost"], reverse=True)
File "/home/neil/.local/share/Red-DiscordBot/data/Steamboat_Bill/cogs/CogManager/cogs/shop/menu.py", line 154, in
return sorted(groups, key=lambda x: x[1]["Cost"], reverse=True)
TypeError: string indices must be integers

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/home/neil/redenv/lib/python3.9/site-packages/discord/ext/commands/bot.py", line 939, in invoke
await ctx.command.invoke(ctx)
File "/home/neil/redenv/lib/python3.9/site-packages/redbot/core/commands/commands.py", line 832, in invoke
await super().invoke(ctx)
File "/home/neil/redenv/lib/python3.9/site-packages/discord/ext/commands/core.py", line 1348, in invoke
await ctx.invoked_subcommand.invoke(ctx)
File "/home/neil/redenv/lib/python3.9/site-packages/discord/ext/commands/core.py", line 863, in invoke
[9:29 AM]
BOT
Steamboat Bill:
await injected(*ctx.args, **ctx.kwargs)
File "/home/neil/redenv/lib/python3.9/site-packages/discord/ext/commands/core.py", line 94, in wrapped
raise CommandInvokeError(exc) from exc
discord.ext.commands.errors.CommandInvokeError: Command raised an exception: TypeError: string indices must be integers

[njhargis]

Looks like this has been an issue since 2019.
https://discord.com/channels/240154543684321280/240302038565519361/623588710449152022