Manual activity &1 &2 &3 is not a pre- or post-implementation step

What causes this issue?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

You want to perform an implementation test for a note that contains a
manual activity. This is a manual preparation step in an automatic
correction instruction, but is also a manual follow-up step in a
different automatic correction instruction of the same note or of one or
more other notes. This is the result of the following two steps:
Follow-up step
The example here is the manual activity <(><<)>M-CI-2222>, which is part
of the note <(><<)>N1>. This note also contains the automatic correction
instruction <(><<)>A-CI-1111>. <(><<)>A-CI-1111> is added as a
prerequisite for <(><<)>M-CI-2222>. This performs the automatic
correction implementation first and then the manual activities.
Preparation step
You have a further note, <(><<)>N2>, which contains the automatic
correction instruction <(><<)>A-CI-3333>. This contains corrections for
which note <(><<)>N1> must be implemented in full. You have added <(>
<<)>M-CI-2222> as a prerequisite <(><<)>A-CI-3333> here. This means that
the manual steps must be implemented before the automatic correction
implementation <(><<)>A-CI-3333>.

System Response

The system cannot simulate the corrections in the specified order (in
implementation tests) or implement them.
Implementation order/queue in SNOTE:
1. <(><<)>A-CI-1111><(><<)>N1>
2. <(><<)>M-CI-2222><(><<)>N1>
3. <(><<)>A-CI-3333 ><(><<)>N2>
This is an error state and SNOTE is not designed to implement manual
corrections between two automatic correction instructions.

How to fix this error?

If this error occurs when notes are implemented using SNOTE, contact SAP
Support.
If this error occurs during an implementation test, proceed as follows
in accordance with the example above:
1. Break the link between the manual CI <(><<)>M-CI-2222> and the
automatic CI <(><<)>A-CI-3333>
2. Then choose from the below available options appropriately:
Create the new manual correction instruction <(><<)>M-CI-4444> in note
<(><<)>N2>. Here, specify that note <(><<)>N1> must be implemented
before <(><<)>N2> is implemented. Add this as a prerequisite for <(>
<<)>A-CI-3333>.
or
In the long text of note <(><<)>N2>, specify that note <(><<)>N1> must
be implemented in full before note <(><<)>N2> is implemented.

Error message extract from SAP system. Copyright SAP SE.