Authorization Bearer Access Token doesn't seem to work

I have a piece of code that passes in a bearer token
```
Map? get authorizationHeader =>
{ 'Authorization': 'Bearer $accessToken' };
```

I get the token and I make this call, but I get a 401 error
```
CachedNetworkImage(
width: 48,
height: 48,
imageUrl: iconService.getRoomIconUrl(
roomId: item.room.id,
iconMetaData: item.room.iconMetaData,
),
httpHeaders: iconService.authorizationHeader,
)
```

I do the same for Image.network and it works just fine. Am I doing something wrong?
```
Image.network(
iconService.getRoomIconUrl(
roomId: item.room.id,
iconMetaData: item.room.iconMetaData,
),
headers: iconService.authorizationHeader,
)
```