Help with AK Interactive Water Gel (Swamp Green)

I'm working on some test bases to see how best to create a swamp terrain for a death army for AoS. After watching this excellent tutorial, I bought some AK Interactive Water Gel in Swamp Green. According to the AK catalogue, it is "perfect in layers of 0.1 to 3 cm", but when I applied a later of ~2-3 mm over my painted/textured base, a number of half moon surface cracks appeared once the gel dried. Furthermore, the gel wasn't anywhere near transluscent, so I couldn't see the texture beneath.

Rather than just repeat the same experiment and expect different results, I thought I would reach out to the community and see if anyone has any success stories with this product.

Thanks in advance!