Can't mine upward with items lying on downstair

[FeepingCreature]

Describe the bug

Can't construct with items lying on a down staircase.

Steps To Reproduce

1. Have tools and items necessary to build up staircase in rock

2. Be standing on a down staircase dug up from a lower level

3. Have required resources dropped at your feet

4. Try to mine Upstair.

Expected behavior

Items should fulfill construction attempt.

Screenshots

Versions and configuration

Version: 572b78f stock

Additional Context

Just noticed: merely mining out and standing in a free space is enough to fix it, the items can be on the staircase, you just can't be also standing on them.

[Night-Pryanik]

Can't confirm on 0.F-6416.