I just tried that hotkey with Chome frontmost, and it worked for me.
Did you change your Macro Group to allow Chrome. As it is it will only be available when Firefox is frontmost:
IAC, have you considered using a Typed String trigger?
I find this works very well. Here's an example:
The Typed String trigger has a SPACE at the end:
";img "
MACRO: Insert Clipboard with Image Tag [Example]
#### DOWNLOAD:
<a class="attachment" href="/uploads/default/original/3X/a/6/a615f5b0a27a70e85d2575dff122ec72b8a1eaa1.kmmacros">Insert Clipboard with Image Tag [Example].kmmacros</a> (2.0 KB)
**Note: This Macro was uploaded in a DISABLED state. You must enable before it can be triggered.**
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![image|493x472](upload://A1btPf4638xHNAws60esaQgG81y.png)