swap_dims issue

[danielabdi-noaa]

I am getting an error IndexVariable objects must be 1-dimensional with the swap_dims call on the following dataset.
Surprisingly, If I change something unrelated to the dimensions I am swapping, namely datetime and time, it works.
If I use 1D lat/lon it works, if I keep the 2D lat/lon though I can't get it working.

import numpy as np
import xarray as xr
import pandas as pd

# Dimensions
datetime = pd.date_range("2024-05-19T06:00:00", periods=4, freq="H")
level = [200, 300, 475, 800, 850, 900, 925, 950, 975, 1000]
lat = np.linspace(-90, 90, 530)
lon = np.linspace(0, 360, 900)

# Dummy coordinates
lat2d, lon2d = np.meshgrid(lat, lon, indexing="ij") # comment this out and enable the next line to get the swap working
#lat2d, lon2d = lat, lon 
time = pd.to_timedelta(np.arange(len(datetime)), unit="h")

# Create data variables with dummy data
HGT = np.random.rand(len(datetime), len(level), len(lat), len(lon)).astype(np.float32)
VGRD = np.random.rand(len(datetime), len(level), len(lat), len(lon)).astype(np.float32)
TMP = np.random.rand(len(datetime), len(level), len(lat), len(lon)).astype(np.float32)
SPFH = np.random.rand(len(datetime), len(level), len(lat), len(lon)).astype(np.float32)
T2M = np.random.rand(len(datetime), len(lat), len(lon)).astype(np.float32)
REFC = np.random.rand(len(datetime), len(lat), len(lon)).astype(np.float32)
LAND = np.random.rand(len(datetime), len(lat), len(lon)).astype(np.float32)
UGRD = np.random.rand(len(datetime), len(level), len(lat), len(lon)).astype(np.float32)
OROG = np.random.rand(len(datetime), len(lat), len(lon)).astype(np.float32)
VVEL = np.random.rand(len(datetime), len(level), len(lat), len(lon)).astype(np.float32)

# Create the xarray Dataset
bds = xr.Dataset(
    {
        "HGT": (["datetime", "level", "lat", "lon"], HGT),
        "VGRD": (["datetime", "level", "lat", "lon"], VGRD),
        "TMP": (["datetime", "level", "lat", "lon"], TMP),
        "SPFH": (["datetime", "level", "lat", "lon"], SPFH),
        "T2M": (["datetime", "lat", "lon"], T2M),
        "REFC": (["datetime", "lat", "lon"], REFC),
        "LAND": (["datetime", "lat", "lon"], LAND),
        "UGRD": (["datetime", "level", "lat", "lon"], UGRD),
        "OROG": (["datetime", "lat", "lon"], OROG),
        "VVEL": (["datetime", "level", "lat", "lon"], VVEL),
        "time": (["datetime"], time),
    },
    coords={
        "datetime": datetime,
        "level": level,
        "lat": (["lat", "lon"], lat2d),
        "lon": (["lat", "lon"], lon2d),
    },
)

print(bds)

# Here is where the issue is
bds = bds.swap_dims({"datetime": "time"})

print(bds)