Saxon

When a string starts with whitespace, followed by exactly 1 readable character, neither @select nor <xsl:value-of> outputs the character in a <xsl:processing-instruction>.
When constructing a <xsl:element>, it is generated as expected.

Amount of whitespace seems to be irrelevant (also tried with some 
).
Behaviour is as expected if the input has

• no whitespace before the 'z'
• whitespace after the 'z'
• more than 1 readable character following

I tried setting @as='xs:string' (https://saxonica.plan.io/issues/3748), but that did not help.

Given:

• whitespace_plus_char.xsl
• Saxon-PE 9.6.0.7J or Saxon-PE 9.8.0.12

expected:

<?xml version="1.0" encoding="UTF-8"?><?s1 z?><?s2 z?><?s3 z?><w> z</w>

actual:

<?xml version="1.0" encoding="UTF-8"?><?s1?><?s2?><?s3?><w> z</w>