This can be for several different reasons:
The resolution exceeds the maximum resolution of the DisplayLink device
To make sure that your DisplayLink device is supporting those modes or resolutions, please refer to this article.
The resolution is not being reported by the monitor
If you are sure that monitor mode or resolution is supported by your DisplayLink device, you can add it by manually adding registry key setting.
The steps below describe this process:
1) Go to registry editor - open Run window "Win+R" -> type "regedit" -> "OK"
2) Add new registry key:
<monitor_type> can be extracted from EDID file located in C:\Program Files\DisplayLink Core Software\Debug. Examples are listed below:
a) file name: BenQ G2420HD_BNQ7840-89A09497SL0.edid <monitor_type>: G2420HD
b) file name: PLE2607WS_IVM5608-2010.41.01010101.edid <monitor_type>: IVM5608
3) Create new String Value
Value name = WxHx0@F, where:
W - Width
H - Height
F - Refresh rate
Value data = yes
4) Restart computer
After this, added mode or resolution should be available for configured monitor.
Please note: this mode/resolution might not work if not supported by the monitor.