As already mentioned earlier here, Mikrotik 11ac products do not support anymore non Wifi standard channels (10Mhz or 5Mhz).
On the product page it is mentioned support 11a/n/ac, so why would the product offer something else?
But I don't know why you do not see "allowed-channels". On my IPQ 4019 device (Chateau) I get following.
Ssetup as AP with 802.11 as protocol, I assume you will need to select the appropriate (allowed) channel/functional mode first before seeing these.
/interface/wireless> info/allowed-channels wlan2
channels: 5180/20-Ceee/ac/P(-7dBm),5185/20-Ceee/ac/DP(-10dBm),5190/20-Ceee/ac/DP(-10dBm),
5195/20-Ceee/ac/DP(-10dBm),5200/20-Ceee/ac/DP(-10dBm),5205/20-Ceee/ac/DP(-10dBm),
5210/20-Ceee/ac/DP(-10dBm),5215/20-Ceee/ac/DP(-10dBm),5220/20-Ceee/ac/DP(-10dBm),
5225/20-Ceee/ac/DP(-10dBm),5230/20-Ceee/ac/DP(-10dBm),5235/20-Ceee/ac/DP(-10dBm),
5240/20-Ceee/ac/DP(-10dBm),5245/20-Ceee/ac/DP(-10dBm),5250/20-Ceee/ac/DP(-10dBm),
5255/20-Ceee/ac/DP(-10dBm),5180/20-Ceee/ac/DP(-10dBm),5185/20-Ceee/ac/DP(-10dBm),
5190/20-Ceee/ac/DP(-10dBm),5195/20-Ceee/ac/DP(-10dBm),5200/20-Ceee/ac/DP(-10dBm),
5205/20-Ceee/ac/DP(-10dBm),5210/20-Ceee/ac/DP(-10dBm),5215/20-Ceee/ac/DP(-10dBm),
5220/20-Ceee/ac/DP(-10dBm),5225/20-Ceee/ac/DP(-10dBm),5230/20-Ceee/ac/DP(-10dBm),
5235/20-Ceee/ac/DP(-10dBm),5240/20-Ceee/ac/DP(-10dBm),5245/20-Ceee/ac/DP(-10dBm),
5250/20-Ceee/ac/DP(-10dBm),5255/20-Ceee/ac/DP(-10dBm),5260/20-Ceee/ac/DP(-10dBm),
5260/20-Ceee/ac/DP(-10dBm),5500/20-Ceee/ac/DP(-3dBm),5505/20-Ceee/ac/DP(-3dBm),
5510/20-Ceee/ac/DP(-3dBm),5515/20-Ceee/ac/DP(-3dBm),5520/20-Ceee/ac/DP(-3dBm),
5525/20-Ceee/ac/DP(-3dBm),5530/20-Ceee/ac/DP(-3dBm),5535/20-Ceee/ac/DP(-3dBm),
5540/20-Ceee/ac/DP(-3dBm),5545/20-Ceee/ac/DP(-3dBm),5550/20-Ceee/ac/DP(-3dBm),
5555/20-Ceee/ac/DP(-3dBm),5560/20-Ceee/ac/DP(-3dBm),5565/20-Ceee/ac/DP(-3dBm),
5570/20-Ceee/ac/DP(-3dBm),5575/20-Ceee/ac/DP(-3dBm),5580/20-Ceee/ac/DP(-3dBm),
5585/20-Ceee/ac/DP(-3dBm),5590/20-Ceee/ac/DP(-3dBm),5595/20-Ceee/ac/DP(-3dBm),
5600/20-Ceee/ac/DP(-3dBm),5605/20-Ceee/ac/DP(-3dBm),5610/20-Ceee/ac/DP(-3dBm),
5615/20-Ceee/ac/DP(-3dBm),5620/20-Ceee/ac/DP(-3dBm),5625/20-Ceee/ac/DP(-3dBm),
5630/20-Ceee/ac/DP(-3dBm),5635/20-Ceee/ac/DP(-3dBm),5640/20-Ceee/ac/DP(-3dBm)