Why wont my IES profilees show correctly?

When I apply any IES profile to a selected light it just intensifies that existing light. It recognises the IES… But nothing happens apart from that extra burst of intensity.

Ive tried the same thing in an older version (4.16 i think it was) and it just worked seamlessly so im wondering if its something ive done wrong down the line or its a genuine bug? Either way its really annoying!

The first screenshot shows the standard light. The second shows the same light with an IES profile applied, using the IES brightness too (I should stress that it’s the exact same result regardless of what IES I plug in).

Thanks in advance to anyone who can lend a hand with this one!
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