On the DM-101, some tap divisions are not available in certain delay modes because each mode has its own delay time range. If a tap division would result in a delay time that exceeds the maximum limit for that mode, it will not be selectable.
For example, in Vintage Mode, the delay time range is from 10 ms to 300 ms. Because of this, only a limited number of tap divisions can be used in that mode. Not all tap divisions will be available, and this is expected behavior based on how the DM-101 is designed. The DM-101 only enables tap divisions that fall within the delay time range of the currently selected mode.
For reference, see the diagram below. It shows the delay time range for each mode and can help you determine which tap divisions are available in each one.
